Keep in mind I had to re-balance the bottom end when using the KB 107's it may save you money to check into different piston options that weigh the same as the stock piston/pins.
Rings, bearings, hand hone, oil pump, pickup screen, clean water passages meticulously. And see what you can do to surface heads or use thin head gaskets.
Maybe get that Edelbrock RPM intake for sale here that's got the head bolt hole already hacked for decked heads. Not pretty but should work. IMHO, worth $150 shipped.
Then spend money on a decent carb if don't have one.
Search around for a good priced less desirable HP Hi-flo 73-76 340-360 manifolds. Or a magnum right side you can grind out to 2 1/2" yourself. Wouldn't bother unless you kept the manifolds under $250.