318 stalls in Drive

Hello, MOPAR Brain Trust,
My '84 318LA stalls when put in DRIVE. I"ve searched this forum and FBBO and found some useful information. But..... I'd like some more input on resolving my particular engine problem.

Here's what I got:
1984 318LA that's been 'cammed' up. It's in a 1975 D100 truck, 727 trans.
Currently idling at 850 rpm, put it in Drive and rpm drops to about 550 and most times the engine will stall if I don't pad the gas a little.
Stock flat top pistons and std. bore.
resurfaced heads, unknown amount
Timing 18 deg. BTDC static
Camshaft purpleshaft P/N: 4120231
I/E duration @.050 241
Advertised @ 284
I/E lift .484 (stock rocker arms)
LSA 108 (originally timed at "0", advanced cam 4 deg. Cloyes chain) This helped some.
Overlap 68
Stock 1975 Converter (i think thats a 1700 rpm stall)
Cast iron exhaust, duals.

Here's the kicker, I know you guys are going to 'facepalm'. It originally had a Weiand Action Plus 8007 intake. The throttle pressure (KD) linkage would not match properly. I installed the cast iron 2 bbl intake and Carter BBD 2 bbl carb with the stock KD linkage.
My reasoning being that the BBD is sufficient in size as the primaries as a small 4 bbl. Just wouldn't have much top end power, which is fine.

How quick does the mechanical advance in the distributor come in? If it's already advancing @ 850 rpm, then when it goes into gear, as the rpm drops back to 550, timing drops back as well because the convertor is too low stall speed, and added together with a way-to-big cam for the convertor, causes the engine to stall. Simple huh?