Of hand, does anyone know the physical (not valvespring) lift that can be put into a stock L36 headed engine?

not sure if this will help or not....

the highest Rocker arm ratio that will fit on stock heads are 1.95'*

sounds like someone wants to cam. but why do you wnat to go so big

For some reason, I think the guides will allow for about .51" lift(give or take .01") unmodified...

Talked to intense(todd), he said .525-.526" of lift.

Reason i asked is i already have 1.8 rockers on it

With stock valve spring retainers and valve seals there is clearance for ~.515" lift. With modified retainers you can gain another .030" clearance and viton valve seals will allow another .020" clearance on top of that.

However, stock heads don't flow at those lifts anyways so it doesn't make a whole lot of sense to run that much.