Chainsaw Repair

Just put a new piston and seals in my 5000. The saw was a Christmas present from my wife in 1980 and cut our firewood for many years. I'm kinda attached to it and would like to get it running good for sentimental reasons.
I had a brittle old replacement gasket that was split at the narrow point right over the crank on the flywheel side. Wanted to see if anything else leaked so I put it on dry and pressure tested at 6psi through the plug hole with the exhaust port and carburetor gasket blocked off. That was the only leak.
Can I fix this with sealant? If so what do you recommend. I could cut another gasket but am not sure what material, thickness,  and sealant would be best. Glad to try a squish test if that's the way to go. 
I ported the exhaust on my 346xp which really woke it up.  Not sure if I want to do it on this one though unless there are tried and true mods.

Just remembered the last base gaskets I bought for these I just got from my husqvarna dealer.   Thinking husqvarna 50. Let me check my info.