Its not what you could call the prize winning stud of the downer racehorse thoroughbreds.
More of a mangy old bugger that has to be dragged to the glue-factory on a cart.
Not THE worst. But pretty shitty. Its a bugger on the digestive system, I'd advise a lot of gaviscon to hand, other stomach soothing meds too. It'll leave you belching camphoraceous and slightly minty, halocarbonesqe fumes for ages, and it tastes like fucking arse on a bun baked in an anus from rectum-dough and made into a rear end sandwich with cheese on top. But what TYPE of cheese....is better left unsaid. Clue? its gender-specific...
Its bad for the liver over longterm. Best saved for an occasional sedative. I can't really estimate doses for you given the tolerance to other drugs. But for nontolerant, 500mg to a gram or so, the latter being fairly high, sometimes I've seen it used in larger doses. But caveat being, this IS in a medical manual from the 1700s when they had no compunction about dosing babies with mercury salts for teething (calomel, mercury (I) chloride, for example, or mercury metal bashed to finely divided metal by pounding with chalk, and known as grey mass), as well as using arsenicals, hydrogen cyanide (well, aqueous hydrocyanic acid, aka prussic acid), lead salts, other mercury salts and oxides and halides and fucking christ only knows what else, using antimony, white phosphorus...hell, their treatment for piles, was to apply nitric acid.
So take the advice with a fistful of sodium chloride, hell, they were still measuring things in grains back in those old books of mine. Sorry I can't check for you, but the books themselves, aren't in the house as I lent them to my GP, the one who is actually a decent man. (not sharp enough to keep up with me if I need to explain anything neurological or biochemical, and he says so himself but fundamentally, a good man, kind and with a good bedside manner. Not a totally illogical panic-infested fuckbucket full of stagnating jizm like certain members of that GP practice)
But nontolerant, certainly up to a gram. IIRC larger doses were also used but thats what I recall clearly. I'd start with less than half that. 250mg at most, maybe 100mg given the other drugs your on. Run it up slowly, even though it'll mean quite a few nonstarters. 100mg increments would be pretty safe I should think, chloral isn't one of those uberpotent things, although it isn't benign in OD like benzos are. Plus I should think too much would give one a real cunt of a hangover. Its closely related to alcohol.
Kind of the bastard child between antifreeze and paint stripper, being the geminal (1,1-) diol of 2,2,2-trichloroethanol. Well sort of its bastard child as ethylene glycol is a vicinal diol (the two hydroxyl groups are on two adjacent carbons, whereas they are both on the same carbon atom in chloral hydrate)
Useful enough in microscopy, as Melzer's reagent for fungal spore testing (I admit it, I'm a mycologist geek, albeit one that doesn't look or otherwise act geeky in the least, outside of my lab

), and certain other purposes. But really crappy to use as a drug. A sedative for occasional use at best and a third rate one at that.
The best thing I can say about it really, is that it isn't paraldehyde. Not a particularly high compliment.