4.3l to 327 with vortec heads swap k1500

I plan on installing vortec heads on a 327 Chevy using the factory TBI and installing the motor in my 1989 4x4 that currently has a 4.3 liter vortec. Everything that I have read says that this is an easy swap and everything should bolt right up.
Has anyone swapped a 4.3 liter for a V8? I plan on keeping the stock TBI system, but I am going to installing the bigger TBI from the 350. I want to run full length headers with after market Catalytic converters with duel exhaust. Retaining the stock engines EGR valve, Oxygen sensors, and smog equipment. After all I need to keep the motor smog legal for New Jersey vehicle and emissions inspection
The TBI manifold for the vortec is very pricey. I have seen where some guys have used an after market vortec four barrel carburetor intake (which is half the price of the TBI intake) and made up a plate that bolts the throttle body to the intake. Would this cause the engine to run improperly or rob the engine of valuable torque and horse power?