A solution might be to make your own gasket out of the thickest gasket material you can find, plus a bead of rtv (nothing wrong with using rtv). Another thing is check your tstat bolts to make sure they bottom out further than the tstat manifold, it might just not be clamping.
86 Fiero GT 4spd - (pending L67 swap: VS cam, GenV) Build Progress
98 GTP - Some mods
[This message has been edited by sco77 (edited 06-30-2013).]