I decided to post a new thread as I posted this in an ongoing, and really this applies more to general than to a specific model.

Good afternoon fellas. About 9 months ago, a friend of mine who owed me some cash found this deal and went ahead and bought the airplane for me. I have not built or flown a propeller driven RC airplane in many years, as I have been focusing on Turbine Jets and built probably more than 20 of them over the past 6 or 7 years. When I was into props, I was into much smaller airplanes than those of this size.

Anyway, my question for you group of knowledgeable guys is that another friend of mine who had a NIB Zenoah GT80 twin sitting on the shelf in his garage has given me a long term loan on the engine (read is I legally stole it ) ( a term we use between the two of us taking things from each other) and the engine is too deep to mount to the existing fire wall, so I took it out and have tacked in place a new firewall the appropriate dimension back (1.3125 inches). Is there a tool beyond eyeballing it for centering the engine so that the prop shaft comes out center of the cowl?

I have never done this before, so please don't assume I have any knowledge of what to do, but for the purposes of the discussion you can assume I am familiar with most building techniques and tools of the trade, on the jet side of things, I mold and scratch build jets.

Pics of this airplane and situation I am in, and pics of where I primarily spend my hobby time, if you find that sort of thing interesting: