What do you use your YJ for? Is it just a daily driver? If it’s only for the street and snow go with the option for the best mileage and road manors. With your situation there are too many options. What axles and tranny do both jeeps have? Is the gearing in both the YJs axles the same? Some of your good mileage on the 95 could be due to the gearing in the axles and tranny. I would talk with a few shops since you don’t plan on doing it yourself. A head swap or after market FI might be the most affordable option. But, the only way to get the same mileage you had before is a full drive train swap (engine, tranny, t-case, and axles.) The swap would be simple for a mechanically minded person. All the components are made for the same body style vehicle. But, that in no way means it would be affordable for a shop to do for you.
If you have any question about my question just ask. We’ll help.
STEP 1: BUILD IT!
STEP 2: BREAK IT!
STEP 3: REPEAT!!!!!