If you go with l92's there is an advantage with the 370 over the 364, the bigger bore will produce bigger flow numbers out of the l92's (less shrouding) and maybe, but doubtful the 243's (although numbers would be smaller than the l92's) seeing as they are used on a 3.900 bore and make big number i doubt there's that much difference from 364-370. Remember flow = power
back on topic, if you go 370 i would highly suggest l92's. they are cheap and there is no need to get the ls3 heads, the only diff is the valves which are lighter. Also get them ported mine flowed i want to say 36x on the 4.030 bore and they picked up quite a bit more on a 4.125. then not to mention the extra 5hp u pick up from the cubes thats worth 70$ imo although u might want to make sure thats not per hole. besides that run stock crank with a eagle rod (bought from the right place they dont cost 800$ like they do on texas speed) and a wiesco l92 piston set at 11:1+ and a nice cam, 500hp shouldn't be to hard. make sure u get some one that knows l92's to spec ur cam they like a bit of split on the duration