HOLD ON HOLD ON[X(] PETER I´m not saying that[X(]¡ maybe my leak of perfect english could make a confusion.Were did I write that affirmation?

BVM engine 91 or 96 will not overheat and I don't have personal experience due I don't own one but I help my friends at the field.
The problem with BVM engines is not realy a problem, is just too much engine for a DYNAMAX unit.
BVM 91 or 96 will over-rev in a DYNAMX easily,same for Rossi 90 with DYNAMAX.
You can use but you cant sustain WOT due DYNAMAX will not absorb all HP produced with bot engines, specially the BVM.
OS runs happy in 21000 rpms and make power at lower rpm than Rossi or BVM.
Rossi runs happy in 22000-23000 depending of which model of 90 are you using.
BVM 91 or 96 can sustain the 24000 K like Peter said.And they perform well because the unit was designed for their engines, remember the rule area.

As I told in previous posts, you can use a stronger engine in a DYNAMAX but you just will overev either one the Rossi or the BVM.
Personally I set a Dynamax unit for a friend with a Rossi 90 older model(shor rodIt hink is the 49R90 were carb goes out with two screws) and he never runs more than 3/4 of throttle but not sustained, but 1/2 constant and airplane flyes perfect. We try WOT in the bench, engine scream incredible but it will not stay together not the engine but DF unit, so in order to keep control we decide to use a bigger pipe in order to control max rpms and decompress the engine with extra shims.

On the other side in my personal opinion, it doesn make sense a person to buy a BVM 91 or 96 to install in a DYNAMAX. MAkes more sense to use a Rossi 90 or 105 in a VIOFAN but either way is not a RIGHT MATCH COMBINATION.

Falcon, go with OS an DYNAMAX and you will be in the right path.Remember to include in your order all pipe and header system,remote needle and pressurized pitot tube.