good, strong, but safe dose. At the very least answer me that?
It is really, really hard to answer dosing questions for someone and could even be considered dangerous. We don't know your body, your tolerance or the quality of product you get. Hell it's hard to tell someone how much pharms to take to get high, and that is a known purity and quantity, Heroin not only varies in quantity (as in fat or short bags) but widely in purity, even from bag to bag from the same dealer. Not even considering cuts, but just simply considering the skill of the chemist and them unintentionally but undoubtedly adding impurities to their product unless they are among the best of the best. And then the cuts on top of that.
That being said, you say you snort 70-100mg for a nice high. I would find some dope that has similar dosing properties and doing less than half of that, so maybe 20 or 30mg. I guess you could do up to 50mg, but if the dope is strong to you at 100mg snorted you could be pushing into dangerous territory. The saying goes "you can always take more, but can't undo what you have already dosed" or some variant there of. This is especially true with IV use. IV enables one to put way way too much drugs into their body in an instant which can have disastrous effects (death), and it takes 10 seconds man. You push the plunger and it's done, no going back. And this is just in the physical sense, same goes for you opening up Pandora's box and I would personally advise that you do not use drugs IV. It's a whole other ball game.
To sum up, use 25-50mg and 25 is the safe side, and 50 is pushing it. This is based solely on the info you have provided and nothing more. The first time I shot up I did about a 1/4 of a point and was totally blown away, although I had very minimal tolerance and I guess the stuff I get is pretty decent. And not it's at a point where I can do a 1/4 gram, and not even be blown away. IV really raises your tolerance, partially because many people turn into everyday, if not multiple times everyday users when the try the needle. I WOULD RECOMMEND YOU STICK WITH SNORTING YOUR HEROIN.
DO NOT COOK IT. Heroin and all opis are very soluble even in cold water. There are many threads with information as to why you should not heat dope and especially pills but essentially you are not increasing the amount of heroin in the shot, and if anything are degrading the product (too much heat) while adding unnecessary cuts/binders/inactive material to your shot, that would have been filtered out if you would not have heated the solution. USE COLD WATER AND STIR VIGOROUSLY.
I find the duration of the high shorter than when sniffing dope. And also different. But I think it all stems from IV use having an instant come up and essentially after a minute or two you have peaked and will not really be any higher, and from that point are only going to start coming down. Whereas snorting has a definite "coming up" period, IV use does not, it happens immediately. For me the intense, intense effects last about an hour and I'm usually quite high for up to 4 hours. I can feel the rush always withing 10 seconds, if not before I have even pushed all the liquid into the vein, and it lasts only for 20 seconds or so now, but when I first started it was much longer. After that first rush, there is about a 10 minute period of very intense bliss and euphoria where I usually just zone the fuck out in some kind of immobilized position. Depending on the dope I can still feel effects 6+ hours later. There is a fine line, even for very tolerant users between the "perfect high" and overdose so just remember that when you try and push it and get that awesome rush you have been chasing after the first time.
Again I would advise that you not trying IV drug use. Especially with heroin, and especially if you already like it a lot sniffing it. It is too damned hard not to do it everyday, for most everyone. There are exceptions, but they usually have specific if not exceptional circumstances that prevent them from being an everyday IV drug user. Most people who try shooting, will at some point have an addiction to it with some degree of seriousness to it.
The cons vastly out weigh the pros when considering IV use. No lie, in the end (as in once you are a **"junkie"**) the only real pro left is the RUSH. But even it gets diminished. So much so that long time IV users have to use very large amounts just to get a very minimal rush. The cons are numerous, viruses (HIV, HEP C), bacterial infections, abscesses, scarring, the social stigma, increased tolerance, physical dependence, exhausted veins, the physical toll that being a drug addict takes on your body, and many more. I would suggest your very seriously consider the consequences of what you may do before you do it.
Hope this helped.