yes, hang on......You could try this. Because they are all just air cooled these days. (which is what the kits contains, two air cooled types)
Get the plate or make a plate to block off the water cooling jacket and buy two of the 20Amp at the link above (same as what the kit has) and parallel them.
The 20Amp's outputs are all run in parallel these days (mine included) to form the 40A total. And that's what the kit will have you do............parallel the outputs
My only unknown is paralleling the inputs. Normally and as stated you need a 4 yellow wire stator to equally limit the saturating coils at 20Amps to each reg..thus not over loading a 20Amp reg
Your 2 yellow wire is 40Amps, paralleling the inputs should share current if the reg's are close in design, which they most likely are within 5% tolerance of one another.
BUT if not close in design, one reg might take 30 and the other 10 during a full'ish load of say 40Amps.......the work around? Measure it and see, if it work, protect it and run it.
http://www.********************/sea-d...ers-79231.html
where ***** = w h o l e s a l e m a r i n e
I'd put a resettable 20A breaker on the inputs ( I run these now on my inputs), fire it up, load it down with a 40A @ 12VDC load and use a clamp on current meter and see just what each input is drawing, if they're both at about 20A........leave the breakers inline and run'um.
Else bite the bullet looks like, get the kit (4 yellow wire stator and 2-815279T and plate and be done