I have owned two of these models and still have one in need of a restoration. I also have 80% of another kit in the closet. Both of the ones I have flown used an OS .25 VF with a pipe and fixed gear. This model needs to stay light for the performance to be what you would expect and if the weight goes up too much, you can end up with a model that is likely to do a snap roll when you pull hard on the elevator. I wanted to build my third kit with a .48 4-stroke and MK .20 size retracts. After flying the heavier of the two finished models, I have changed my mind on the retracts and probably the 4-stroke as well. I do not see any problem with the .35 engine, but the retracts IMHO are too heavy for so little gain on a model of this size. Use the Williams Brothers thin wheels to lower drag if you like, but I would not build this model with retracts if you expect it to perform like a pattern plane should.

John