What kind of gearbox to use on high power F6 ? Options

[speedsterms]

Hi all,
I leave in France.
I use to have some 911 (3.2l, 993RS Club Sport, 993 RSR, 993 c2)
today I am on another project : 917K Replica.
with a mid mounted engine - the reason why i am asking my question here-

My engine will be a high rev/high power aircooled 3.6l.

I have planned to mate the engine to a 915 gearbox with flipped R/P. but I was told by my mechanic that the 915 will not handle the torque. even if I improve oiling and cooling and add a wevo bearing retainer.

I had a G50 (which I swap to the 915) as it was not usable. impossible to flip R/P. and flipping the gearbox is not acceptable to the CV joint (too much angle) .

I wonder if any one of you have tryed to install a cayman 987.2 gearbox (G8740 to be precise, not the fisrt gen) on an aircooled flat6 ?

Is there any kit available ? (adapter plate)