That's what my friend is doing. He's got his 2006 Western Star/C13 470 Cat tri-axle dump for sale and just ordered a brand new Star glider kit that's set up and wired for the old 400 B model Cat he is building up. He's tired of the rough running, underpowered and grossly fuel thirsty "new electronic engines."
I was at his place and we had the old B model running (before the rebuild) and he set his beer bottle on the valve cover. Didn't even put a ripple in the liquid and I got the video footage to prove it. Try that with a new Cat. Should be a nice truck, all air ride, sleeper and a 19 foot box. And even after building all new engine, wiring, hoses, trans, rears, suspension, it will still be way cheaper than new, and more efficient to operate. If I had a shop, and the money and time, I'd like to do the same.
Anyone got a mint 1988 R model Mack E6-350 they want to trade for a new Paystar?