Converting to fuel Injection

Looking into the Howell Fuel Injection conversion kit. Had a few questions though if anyone can take the time and has the knowledge to help me out. I plan on doing a full exhaust, headers to muffler first, then the fuel injection conversion.
I've done a lot of research on the injection kit, so my main question is do I need any of the emissions vacuums/hoses, or does it not matter? This jeep has had either the nutter bypass or something similar so all the emissions vacuum lines were taken out and bypassed.
The other question is can I use the stock Air intake setup afterwards? I plan to upgrade that down the line as well since it uses the crappy rubber hose/pipe.

Small thing, if anyone would like to recommend an exhaust kit/muffler that isn't loud or drone heavy.

 

I have had a Howell setup on my '86 since 2007. This was installed by me in a weekend. Most all of the crap you see under the hood gets removed and it is smog legal, and it does use the John Nutter bypass. Headers would work just fine, although they do give off a lot of underhood heat. My ignition has the Team Rush upgrade for the 258 which is a great improvement and inexpensive. The Rochester throttle body has around a 4" diameter throat and your existing air cleaner can be opened up with a little fabrication to work and I would recommend using it so the engine can get fresh air. The Howell website has a set of instructions you can download to get an idea of what is involved for installation, You can get an emissions legal or not kit:https://howellefi.com/product/tbi-kit-1987-91-yj-wrangler-offroad/

 

Ok that gives me some ideas if I go that rout. I stumbled across the Holley Sniper EFI systems today as well and am considering that too since it doesn't require a separate ECM, it's built in. I definitely want to still have air intake from the front, but just want a different/better setup than the stock rubber hose and the clunky circle turtle shell filter. In terms of emissions, I'm glad to hear I don't need them considering where I live doesn't require them on vehicles over 25 years old. My other thought behind the Holley is it comes with a clamp on exhaust sensor rather than having to get a shop to weld into the exhaust.
Can you explain the Team Rush ignition? I haven't heard of that before.

 

The Team Rush Upgrade for the Jeep '78-'90 258 has been around for a long time. It uses the oem MotorCraft distributor with some changes made to make better spark. The parts list consists of an adapter, distributor cap, and rotor from a 1982 Ford 300 six. It does require a new set of spark plug wires either from a Jeep 4.0 which don't fit very good or I would advise making a custom set from MSD. The wires provide the least amount of resistance and will last longer.
Using N.A.P.A. part #s:
Adapter FA139
CAP FA136
ROTOR FA159
The cap is of a larger design using brass contacts whereas the Jeep uses aluminum contacts which can corrode, the larger cap and adapter helps with sparks jumping around inside the distributor. The rotor is of a taller design to help with sparks making contact with the distributor base. You can give the spark plugs more juice by grounding out the head by connecting a #10 copper wire from the battery negative to a threaded hole location like the coil mounting location. It is of a similar design to the G.M. high energy ignition used in the older engines.
I also switched to a N.A.P.A. part #FA136 coil, just make sure your coil is good. The spark plug gap will be increased to an .045". The is a bit of info about this on the net if you want to look it up:https://www.jeep-cj.com/forums/f2/teamrush-ignition-upgrade-11416-print/, amongst other sources.