What would you do? Slant performance

I always figure you should start with gears and exhaust.
That way you'll make the most of every engine mod.
But with a /6 the head is the weakest link in flow and compression. I'd make a trip to a scrapyard and pick a couple of heads and practice porting on one of them will saving the other for the final with milling and porting.

So I'd start with as much gear as your willing to live with.