?'s about modifying factory GM TBI

[toddshotrods]

This is for the 86 Cavalier, TBI, four-cylinder in my trike. It is a temporary stand-in until I build an Ecotec to replace it. The engine is completely stock right now, with the exception of the air cleaner.

First Question
It has a single oxygen sensor, located about six inches from the head, in the collector area (factory "header" with short tubular primaries). I want to split it into true duals with dual collectors.

Will the oxygen sensor provide the correct signal if it is exposed to only two cylinders worth of burnt gases, or do I need some kind custom setup with dual sensors?

Second Question
The throttle body is mounted like a traditional carburetor. The injectors fire right down the pipe into the throttle body. At idle, the butterfly is closed and the fuel kind of bounces off of it, and is sucked in around it. I want to fabricate a new intake with the throttle body mounted almost horizontally.

Will the engine vacuum be enough to pull the fuel spray into the engine, or will it puddle and stumble?