Nothing special is required to put the AL head on, just the normal head gasket. You're only going to pick up maybe 10 hp, so it's not going to make a whole lot of difference driving. You might want to call Isky or one of the older cam grinders and ask about getting a little more aggressive profile. You'd have to send them a good used cam though. They did that for my old 196 OHV. If they can increase lift 0.10" and duration about 20į you'll notice a bit more power in mid range. Not much will pep it up on the bottom end -- it's just a long stroke six that takes a few seconds to build up revs.
If you're looking for a more fun to drive car and/or just want more power you might be happier with an engine swap. I can tell you that the difference between the 90 hp L-head and the 125 hp OHV 195.6 is VERY noticeable. You might even be satisfied with that, but the 196 OHV has some maintenance issues and parts are expensive and hard to find. You can find anything for it, but if a water pump goes out on a long trip you'll be overnighting a water pump from somewhere. If it goes out on Friday night you'll be stuck until Tuesday even then (call Monday morning...).
There are a couple engines that easily swap into that chassis. You will need the transmission with the engine no matter what (unless you do the 196 OHV swap). The Ford 200 or 250 six is a popular swap. The 200 has about the same power as the 196 OHV but parts are much cheaper and easier to find. The 250 would be the one to get if you have to buy an engine -- a bit more power in the same size package. The second most likely candidate is the 2.3 or 2.5 EFI engine from a 90s Ranger. It has to be the one with the intake that curves over the valve cover. The Olds Quad 4 has been swapped in, but requires an expensive bell housing or trans adapter.
The engine bay is narrow on those cars. To swap in a V-8 (the SBF is a good candidate as it's a couple inches narrower than the SBC and other SBs) you have to cut the "humps" above the upper front suspension arm mounting points off. Easy enough to do, and they aren't structural. They were part of the 50-52 Nash Rambler suspension design. When AMC reintroduced the 55 Nash Rambler as the Rambler American they didn't make new inner wheel well panels -- the same were used 50-55 and 58-63. It's still a tight fit for a V-8.
One of the narrow V-6s seems like a natural fit, but the accessories stick out way far on each side. A few hundred in custom "hot rod" brackets will fix it though. Same with modern fours. Most in rear drive vehicles have intakes that stick way out to one side (the Ranger motor being an exception). You could use a front drive type engine as they are usually compact in the intake area, but most of those don't have rear drive trannys that easily bolt up (the GMs do though), and you would have to fab mounting brackets (no big deal, you'll need to do that anyway).