I wouldn't use the KB400 if you are going to have a pair of 80cc heads, your compression ratio is going to 10.5 and since this is a street cruiser you don't need that , building to use 89 octane is a better idea than 93 or more.

A flat top piston would be a much better choice , the Speed Pro 2315 will not require as much decking of the block to get it close to zero.

I just checked the KB site , they say 10.5 with an 80cc head , but they don't tell you that's is after you cut .024 off the block to bring it to zero. If you just skim the block to square it then your compression will be 9.8ish, which is better.

I'd pick a better cam also.