350 Chev to 400 Small Block

[David Sagers]

Looking for someone with experience modifying and setting up a TBI fuel injection system. 
I am replacing the tired 350 engine in my ¡92 Suburban w/TBI.  Instead of going back to the stock 350, I want to install a small block 400. I¢ll also add a few extras like better flowing heads, a mild cam, headers and a free flowing cat and exhaust system. 

This combination will require more fuel than the stock combination. Small block 400 have been around for many years and I¢m sure someone has done all this before, and since I don¢t want to re-invent the wheel, I¢m looking for information about how to feed this engine and how to get the fuel mixture correct so its not running rich or lean. 

Some of the options available are 1) Turbo City offers high flow throttle bodies, high flow injectors and computer interfaces to make the speed density system work with a cam that has longer duration than a stock cam.  Do I just add all their high flow stuff and hope it's close?

2) Edelbrock sells a complete, tunable TPI system to replace the factory TBI, cost is $1200. 

3) Several companies offer computers that intercept the computer signal and modify the fuel and timing curve according to adjustable settings. 

Finally, 4) New chips for the factory computer are available from after market performance companies to compensate for the bigger engine. 

Anyone out there been through this before? What works and what doesn¢t? Thanks in advance.