1500USD to build as much horse in a 360 as possible. What would you do?

Maybe you could get the casting numbers off the heads and start looking around the internet, to find out the combustion chamber volume. They're probably around 76cc or so.....anyway, if I remember correctly, the problem with the 360s was the pistons were usually "dished", which dropped the ratio AND were a little "deep in the hole" @ TDC. I think it's not hard or too expensive to find reasonably priced hypereutectics that will give you around 9.8 to 1.

A lot of piston manufacturers' websites will have graphs that show a particular piston's compression ratio, based on which cc head you've got. Maybe you could shot peen and polish the rods as well.....if you get free access to that machine shop.

Yeah, that engine kit sounds good to me....