A 'piece' ? You mean a square of blotter paper?
You could get a vial that holds say 10 ml and fill it with vodka (nearly exact or exactly 10 ml) and throw in the blotter - then wait and or stir, also buy a small 1 ml oral syringe (no needle, just a measured / marked barrel), the LSD will dissolve into the vodka - the alcohol will act as preservative (though close the vial so that there is no serious evaporation!
Then each ml would be 120 ug.. dose easily by ingesting the measured liquid solution. This would be a form of what is called volumetric measurement.
It's possible for a blotter paper square to hold about a mg or more, but more than that and thicker paper or larger squares are needed.
Unlikely there is actually a 1200 ug hit that would be very rare, but it is not impossible. To be safe, (is he reliable and will he get it lab tested in NL - that is free), assume that it is strong and follow the above instructions.
But seems like you need another talk with your 'friend', I mean what is he thinking you will take for your first time ??
Even 150 actual micrograms is about double of what I would recommend for a first time!
Unfortunately in most cases dosages are exaggerated, this is proven.