#4 - see that bolt that holds your dipstick tube to the IM, just drill another hole half an inch above that.
The 2.3 IM is probably more restrictive overall because of the tumble flaps, and the only benefit to it is that it supposedly helps with low end torque. Honestly it's not worth the effort to use it, since its will require a new wire harness and ECU. If you ever get an aftermarket IM like Cosworth, it would be a complete waste of time anyway.
Also it should run OK as long as you don't WOT (floor pedal) till you get a tune. The ECU is able to make adjustments to the A/F ratio up to %23 off from the manufactures settings, however at WOT the adjustments are disabled.