I should get the lightnings today, and need gaskets. I've heard this ex Merc Master Mech's stuff is superb. Great reading on his site.

http://www.mooreperformance.org/index.html

I used Merc exhaust manifold gaskets on Lightning headers with great success. I also had several studs installed in the heads for the manifolds where possible.
I used double nuts on the studs and socket head cap screws everywhere else. The studs make installation easier in many cases because you don't have to struggle to hold the gasket in place. And, the double nuts really kept things nice and tight. You will need crows foot wrenches to get to most of the nuts on the studs.
I ran everything for a while until all warmed then re-tightened everything. After that I checked a few times, then just check for tightness maybe with oil changes.

Good luck.

I looked at the Merc gaskets and they did not seem to mate up well to the Lightnings. The gaskets that Lightning supplies worked well.

I use Fel Pro header gaskets. I have used them for several years now and no problems.

I also used FelPro gaskets with no problems.

I checked this moring with my local auto parts store. They canget the Graphite impregnated sandwiched gasket that Gil Gil sells for $24, for $13.

I used Fel-Pro #1411 on my previous boat with Lightnings, worked perfekt.

Fel Pro 1410 here.

What is the difference between #1410 and #1411?

MR GASKET - the grafite ones.
I have even reused mine a few times.
NO LEAKS