Ed,

You've gotten some good replies already it looks like. Tom designed this plane around the YS and OS (Hanno) 61s which were the engines to have in the day. It was intended to have the engine mounted inverted with an enclosed pipe through the belly pan. I made quite a few MK IVs after Tom quit making kits. Dan Hines of Carolina Custom took over from me in 2003. Dan still makes the kit and last I saw it was just under 300 direct from him. I don't know what wait time is but I think there is a wait(very nice workmanship though). People have powered MK IVs with all kinds of engines. A piped YS 61 2 stroke works well as BL said, I think the YS 110 or new 115 4S would be great but the fit will be a little tight. I would like to have a MK IV with a JETT 90 FIRE. I looked at the kit being auctioned now. It looks to me like someone has cut out the top of the engine compartment maybe thinking to mount an upright engine as was done on the T2A MK 3. MK IVs did not come with that cutout so that might be a concern. I have doubts Tom made that kit as I never knew Tom to use the white primer or the carbon tow I can see in that fuse. I can't tell much about the wing cores, looks like Obechi but I don't know who might have sheeted them. I don't think Tom ever offered a sheeted kit but I could be mistaken. Good luck, I think you will be happy with any of the T2A series.

George T