I am affraid I do not see your point
In my design, below cowling is an ait intake.
Carlos.
I think that Greg was suggesting that your new cowling for the larger R-4360 may not have been ideal. Since the original R-2600 being as large as it was in diameter there was a lot of room within the cowling that could have been retained for the R-4360 accessories and such. The only real change would have been in the overall length of the cowling to accommodate the longer R-4360 while the area underneath the engine would have been allocated to engine air intake, oil coolers, and associated components of the engine exhaust.
I thought I was being edgy and over the top in wanting to build an Avenger powered by an R-2800 (which is smaller in diameter than the R-2600 by the way) and swapping out the three-blade propeller with a four-blade propeller.