Classics but dated
I agree with briand, Skyranch is the best, but it is not an builder manual. If you want to know every thing about aircraft engines however, there is no better book IMHO.
As far as Tony Bee's (RIP) great books, I have the red, yellow and blue covers. I bought them in the 80's. Nice reference but somewhat dated. Also a lot of it does not apply to RV's (fabric, welding steel tube, fiberglass planes) as you say.
Of the three books I have the FWF (red cover) might be the most useful to a RV kit plane builder. I never read "Engines". FWF gets into vacumn instruments, venturi tubes, mechanical gauges (capillary type) and so on. Alla good stuff but chance is you will have a digital engine monitor. Still the basics are good to know.
The whole plane building thing has changed for one reason, WWW, world wide web and Google. There is not much you can't find on the web or in many special lists like this and others. Now you can go into the work shop of 100's of builders all over the world from builder web sites. When these books where written it was not that way.
FWF does have some pearls of wisdom. I am keeping them for reference.
If it helps you in any way, avoid one gotcha, boo-boo, a major/minor mistake or reduces time to get into the air, it is worth it. You can sell it when you are done. You also may find them used on eBay. Some one one the list may sell you the whole set. To me books are a bargain and well worth it. Read it, keep it or sell it. I think you will want to hand on them. If you are new to building its a good primer on engine installations.