I did a CV swap in my bump and it has to be the easiest IFS swap to do. You end up with plenty of room for any engine. I have not read a single complaint concerning engine clearances. I paid $250 for my CV IFS and another $200 for 1 1/2" drop springs. All in all with drop springs it can be done for under $1000. From what I have seen for pricing on disc kits plus the expense of rebuilding your axle than adding pwr steering. You will be tons of money ahead doing the CV IFS. You will have to run a min of 16" wheels to clear the 12" brakes.

The inexpensive rear swap to go with it? MN12 IRS out of '89-'97 TBird, Cougar or Mark VIII. Many came with disc brakes. Yep I put one of them under my bump as well. All in all both swaps can be done for around $1500. You end up with 4 wheel independant suspension, 4 wheel disc brakes, pwr steering and outstanding ride & handling.

 

I still have Henry's original design but with a Toyota power steering conversion. So far I like the conversion. My springs are most definately shot but the rest of the suspension seems to be in good shape. I rebuilt the brakes (stock) and not sure if I'm gonna like them or not, haven't driven it enough to make a good judgement (in and out of the shop doesn't count!) nor even had the shoes broken in yet. One thing I am considering and would suggest is a good sway bar, at least in the front. I know from driving other rigs, Ifs or straight axle, a sway bar makes a world of difference when going through corners, expecially at highway speeds. Its something I'm looking into aswell, and would like to add to mine.
I think the biggest thing to consider is what you look for in a vehicle's ride related to how much you want to spend and how much work you can/want to do in order to achieve it. If you do the work yourself, you can get into a quality Heidts kit for around $1500 give or take.
I can guarantee that with the Toyota conversion, rebuilding the brakes, upgraded tie rod and ends (from MF) and new steering column, I'm gettin close to that. Now add the disc brake swap and sway bar and I'm probably over that cost and Then add new leaf springs and a drop axle (to get it back down in the front again) and I'm surely into the front susp. $2k or better.

It's really up to personal preferance and what you are looking for in terms of ride/handling quality.