Well, if it helps...
The 42 looks to be a bit of work, given you must drill the case. The OS venturi (20-46) fits just fine. I personally would set it up how people have successfully set up the LA 40 or LA 46.
The 42 is a high Rev engine. For RC, there's some pylon race guys who love them, although may not be legal for many events. It's been a long time since I hung around with them.
I've had plenty of success with the 40 LA run with a TT 11x4.5. You might look into the 12x3.75 APC also. The 42 does like to Rev.