Don't buy Robart 605 retracts- i had them in a top flite mustang and they are worthless. the Cjs may be ok but a better set is the Robart 700 series air up spring down retracts with 7/16 oleos. these are good strong retracts which will be a good match for this plane. Another possibility is spring air 100 series air up spring down retracts with 3/16 wire struts (
www.retracts.com). Spring air retracts are very well made and are very strong.
I flew the top flite p47 for 3-4 years - it flies very well. you will like it. mine had a super tiger g90 which has about the same power as the saito 100 and this was good power for this aplane if built with film covering. if built with fiberglass you should go with a 120 engine.
Ed