Is it me or do you keep moving the goalposts?
Your original question was 'what if a/c a with engine a was developed to accept engine b?'
It seemed to become 'what if a/c a was developed with engine b from the outset?'
We now seem to have moved on to 'let's try a/c b with engine b'
I daresay lessons learned with the P-43 were incorporated into the P-47 design but the P-47 definitely replaced the P-43, rather than addressed its shortcomings. I wouldn't describe the issues with the R-2800 as a bottleneck but it certainly introduced delay into the program.
OK, so if I understand it correctly, we now stand at how would the P-36 have fared, fitted with the R-2600?