Interesting, I hadn't thought of the head installation process related to the camshafts. Typical head installation is with no valvetrain, and then the rockers etc, are installed with the crank at TDC etc. I'm sure you have read the install manual instructions, that might be the best way.
My engine when I did the timing parts, I forgot to confirm the TDC before loosening the jackshaft bolt(I was impatient at that point taking off parts). The heads both(the cams etc) spun to an equilibrium point. I didn't loosen any rockers, I did some hard figuring on where the two heads(cams) needed to be. I slowly rotated the crank towards the proper TDC, and the cams along with it(three sets of parts). I didn't hurt anything thankfully, though it's possible some valves kissed some pistons. It's a big deal to place the crank assembly at TDC, everyone should always begin with that, before loosening any important bolts.
FYI, you have a later SOHC right, it takes the FL-820S filter yes? If it was mine, I would locate and buy the older oil filter block adapter. The old one is SAE, not metric, and it accepts the larger FL-1A filter. Since you have the engine apart, it's a free upgrade if you can get the part, no extra labor to install it. The 4.0 engines have the oil filter vertical, and there's plenty of room for a much larger filter there. The FL-1A is a full quart size, the FL-820S is about 2/3 of a quart. In the SAE thread size, there are also other filters even bigger, like the Super Duty size etc, 1.5 to 2 quart filters. I'd want at least the 1 quart FL-1A, it cost the same and is very common. On my 302 I'm going to use a relocation adapter and end up with the same 3/4-16 filter thread size, and a larger filter to gain capacity for severe duty use.