Using older 350 engine in 1991 K 2500

[No Leaks]

Guys,
I searched through so many threads, and did not see anything like my issue. If someone else has already posted this, please bear with me. This is my first post.
I have a 1991 Chevy K 2500 work truck. Everyday driver. It had the 5.7 TBI. Engine blew on me, and needing it ASAP for work, and not being able to readily find another 5.7 to do a swap, I located and got a 350 4 barrel that was in a 1978 full size K5 Blazer 4WD. It was running a Rochester Quadrajet. I removed the intake, and took my TBI intake to a shop, and had it modified to work on the older 350.
I have had nothing but issues since then, the least of which is about 6 - 7 mpg. (this has been really great, since I live about 40 miles from town) I am fed up with the situation, and so I plan to
1. Get a 65K HEI distributor, and get rid of the current one
2. Put the 4 barrel intake and Quadrajet back on the engine
Here are my questions:
1. Since I have an electric fuel pump designed for the TBI system (which was recently replaced), will an aftermarket fuel pressure regulator bring the fuel pressure down to what the Quadrajet needs?
2. Doesn't the 700R4 transmission have electrical components, and will this affect the 700R4 transmission, as far as shifting goes? It does have the kick down cable.
3. Are there any other issues that I may encounter?
Any help would be greatly appreciated, and thank you in advance.

[tblake]

Does your 78 350 have the fuel pump on the block? I guess I am a bit confused on how you made it work.

[No Leaks]

Yes, it had the mechanical fuel pump when I got it, but I placed a cover over the inlet. I have yet to convert it back to a carb, but it is my intention to do so. This is why I am asking about issues that I can expect to encounter.
When I put this engine in my truck, I had my TBI intake modified to fit on the older 350 heads, so I did not have to change the TBI system that came stock in my truck, and I was able to continue running the TBI system.

[777stickman]

I suppose a pressure regulator would work. Needs to be set to 5-7 psi for the Q-Jet.

As far as the other issues you may want to recheck the base timing and also check for vacumn leaks.

[Elbert]

save up some $$ and buy a GM crate motor for your truck....something like $1.2K with 3 year warranty and 100K miles.

You certainly are not going to gain fuel milage by going with a carb setup.

Yes you could use a regulator to control the fuel pressure.

ON that year model truck I don't think the ECM interacts with the trans at all. You do need the speed sensor but I think thats part of the transmission or trasnfer case (VSS).

What are you going to do with the ECM?