Automobile(s): 64 Coupe Deville 78 Eldorado 85 Seville 94 Fleetwood
Re: 429 torquer rebuild
The 429 is it's own little world. Very little interchanges with anything else and nothing with the newer 472/500. You can get a cam custom ground, though. Porting the heads and port matching the intake and exhaust helps, as well. The biggest problem for these motors is they can't breathe and while there is only so much opening up you can do anything helps. There are no headers available but the car can have true duals mounted by a good shop(2.5 inch is as big as you can go). Flowmasters and a pair of resonators at the back sound good and the resonators help prevent fluctuation of PSI and that "tin can" effect, too.
Also, the Quadrajet intake from the final year for these engines(67?) is a big improvment, both in carb choice and flow, over the 64 intake. By cutting out the base of the breather and welding in a newer QJ piece you can camouflage this rather well(and by opening up the backside of the breather you can increase the airflow without being obvious about it).
Oh, it IS possible to put in bigger valves if you know a good machine guy. I found a write up about this once but lost it in a comp crash. Again, they just can't breathe so this *might* be a worthwhile mod.