I am running a R-block 347 stroker with twin T04e turbos. Dynoed at 535 rwhp and 585 rwtq at 9 psi.
Some people say that the R blocks don't stay cool on the street due to the siamese bore but I haven't had any problems. Mine runs around 180-190. (180 stat)
No idle problems.
Driveability issues? Only the one listed below.
Traction can be a problem. I have 275/40-17" Nitto drag radials on the rear. Yes in 1st gear, and in 2nd when the boost comes on. The Nittos really work well though - better than any other tire I have tried. I just try not to do anything stupid and always make sure it is pointed straight before getting on it.
The 17" wheels are not period correct but then again neither is that big 4" thick intercooler standing straight up in front of the radiator.
Mike