Oh dear God! 318 stroker

273 said
There probably no kits anymore, theres 3.58 cranks with 318/340 main bearing size.
You'll probably need custom piston, but you could have the block check for a possible 4 inch bore or mill down a 318 piston are possible options.

There are available 3.58 cranks w/a small journal available.
Manicini racing is one place

273 said
Why not just bore sixty thousands and have a 328 only 12-21 cubic inches shy of your goal.

edit guess that don't fit the no less and the 4 overbore would be out too.

That and your off set stoke crank!
Piston cost is the bummer.