I ran a 228/235 @.050 duration hydraulic flat tappet cam ground on a 112 installed on a 108 in a 454 mag with stock exhaust with no reversion. I think this is getting close to the max for stock exhaust. Hope this helps.

I second wette on the experience on the 112, but I didn't think that combo was on a 112?

All you have to do is what I did with the stock exhaust
Get some stainless pipes and weld them in the risers to make a water jacket down towards the back of the boat.
Mine are about 14 inches long welded in each riser pipe.
In essence I have "dry" exhaust and I run a 110 LSA Choppy as **** cam with 7 degrees of overlap
No reversion at all
Jason
best of all this mod cost me about 35 bucks and stainless steel welding rods can be gotten at any welding supply company for a few bones.