What ECM should I use for my Mopar 440 conversion project?

[Brian Roth]

I have sourced a wiring harness for my Mopar 440 to GM TBI conversion
project. It looks like I will be getting the harness from a 4.3 Astro van.
According to my research using AllData's wiring diagrams the 4.3, 5.7 and
454 harnesses are essentially the same. It looks like I may have to reroute
a few wires. I will probably be getting all the sensors as well and I will
attempt to use the Astro van fuel pump suitably modified for external use as
I have done with my Ford 5.0 EFI powered  Mitsubishi pickup. 
	
Now I need a throttle body (which I think I have located) and an ECM.

Which ECM should I use? Can I use one from a 4.3 Astro or S10 or do I have
to have one from a V8? Doesn't the computer determine engine speed from the
distributor which would make it off by two cylinders if it counts every
pulse if I use a 6 cylinder ECM on an 8 cylinder? Do I need an ECM for a
truck?   It looks to me like the truck ECM's and the car ECM's do not even
have the same connectors.

How about the distributor pickup? Someone wrote me that I can put a GM
pickup in my mopar distributor. Can I use a pickup from a  4.3 or even a 2.8
for that matter or does it have to come from a V8. How about a Caddy 4.1? Do
I have to start with a mopar dissy that has no advance or can I just disable
the mechanical and vacuum advance on my current dissy? 

My primary goal in doing this conversion is to improve the fuel economy on
my motorhome which got 5 mpg on our last trip but should get about 7 mpg
with a properly tuned carbueretor (Now using a Quadrajet instead of the
stock ThermoQuad). I am hoping for about 9 mpg after the TBI conversion.
What kind of mileage does a 454 TBI powered rig get when it is working hard?

Brian
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