It sounds like you have a nice setup as is. Don't forget if you swap to a 4 speed that you'd need the "hump" on the tunnel and a 4 speed console in addition to the clutch parts -- not a big deal, just a few more line items on the list. BTW -- if you need the dimensions for installing the hump I can hook you up via TAC and/or 78TA. We have several posters who have done that swap.
I am in the process of planning Engine #4 now. There's nothing wrong with my current 400, but it's not what it could be and given that it was assembled with cast rods (race-prepared, but still cast), an old-school cam, and 2 piece stock valves on a 500557 casting (the lighter late 75-75 block) it's just not all it could be. I have a earlier 481988 block and a set of 6X-4 and a set of 6X-8 heads. I am looking at using this heavier block bored out to between 0.040" and 0.060" and a stroker crank with 6.8" Chevy rods for maximum displacement. The 3.000" journals will allow higher RPM than the 3.250" journals found in the 428-455 blocks, and the "long" rods will make more torque. The rods will be forged, as for the price of those these days you can't afford to NOT use them. For a cam I'd like to use a solid roller lifter grind that has a profile equivalent to the Comp XE series hydraulic cams -- I don't want the wild grind normally associated with solid llifters, but rather I'm doing an end run on the EPA. As you know they persuaded the automakers to switch to oils that don't contain ZDDP, an essential component for flat tappet cam/lifter combinations. As of this point if you are running a flat tappet cam you are dependent upon the ZDDP additives on the market. The fly in the ointment is that ZDDP shortens the life of catalytic converters, and if an additive is on the market then it's possible that any Billy-Bob could put it in his new car. That would screw up the converter, dirtying the air, so I expect that the EPA will remedy this problem shortly by outlawing manufacture and import of ZDDP -- just like they did DDT, R-12, and any number of other compounds. If that happens, all the muscle cars using flat tappet cams will be 1 oil change from extinction -- which is really been an EPA agenda item all along. By going to a roller cam I'll just miss that whole unpleasantness and happily continue consuming hydrocarbon resources well into this new century...
Best of all, when assembled and in the car, you won't be able to tell the difference between it and a vintage stock 400...
