Cody,

Glad to be of help. Of course, if the engine and pipe on the stand are changed, then my commented approach doesn't quite apply. The engine, if it still has good compression and you prop, plug and fuel it right, will approach 15K rpm (probably more like 14.5K on 10% nitro and an 11x7) but that is dependent on proper pipe length as well. You might get the engine there but in so doing, you'll likely also have to change the header length. If the exhaust system is routed for the design of the model (it's nice to have the exhaust diverted out the bottom), getting the engine in it's optimal RPM range might result in the exhaust system not working for the layout of the model.

I have to say I'm sort of commenting in the dark a bit as we don't know what pattern model you're talking about nor how the exhaust is setup in detail. Can you take some snaps of the model with good side and top views. The design of the model also affects what type of flight envelope it should have. Given the vintage of the engine, you likely have a late 70's, 80's design (i.e., ballistic pattern) but it could also be that an older design engine (short stroke) was used in a later pre turnaround (long stoke) pattern design.

Looking forward to seeing some pictures!

David