This
'93FSM will be your best friend for the tear down/rebuild. I know yours is an '88, but the 3.0 stayed relatively unchanged through its run, and the '93 manual will work w/o issue. The FSM also contains the 22re specs, tear down procedures, etc.
If you aren't going to rebuild the entire motor, you can't use the MLS, both of the heads and the block have to be prepped for a metal head gasket at a machine shop, simply being flat isn't good enough. If you don't don't have perfectly smooth surfaces the metal head gasket will leak very soon after installing it, this happens all the time on Supra forums I belong too. The 7m is also prone to BHG especially under boost, which metal HG and studs resolves rather easilly. A lot of builders ignore the advice and just have the heads prepped and not the block, and often have a water in the before they even begin boosting the engine. Since you are going to do an in truck rebuild, just send the heads out to be checked/rebuilt. I would port match the heads before sending them out, better airflow is always beneficial. You might check around and see which shops do the head work for the local Toyota dealer. The shop I used did everything for me, including adjusting the valves, and installing new torque-to-yield head bolts in the heads. All I had to do was drop them into place and torque them down.
You must use new head bolts regardless of the condition the originals are in. The oem HB's are torque-to-yield and can never be retorqued to the proper value. The reuse of TTY's is the number one reason for reoccurring BHG's w/the 3.0. Buy new TTY bolts from the dealer, new standard bolts from enginebuilder.com, or ARP studs from whomever still carries them. ARP will cut you some if you send in one of the oem ones, but I never got a quote on what the cost would be. At the time I rebuilt my 3.0 I went w/ new TTY bolts, only ARP studs available at the time were through DOA for $185/set.
You must also replace the knock sensor wire, it gets exposed to heat and becomes very brittle and breaks as soon as you start to remove it. Toyota as well as as other mechanics recommend replacing the knock sensor as well, due to its location it is cheaper to just replace the KS w/the wire AFAIK, no one has ever actually bothered seeing if the KS goes bad, or just the wire. If you don't mind the risk of going back in and replacing the KS($165), you might try just replacing the wire, other than removing the clip the KS isn't touched.
I would have the injectors cleaned and rebuilt as well, runs anywhere from $6/each for cleaning to $32 for rebuilds that are balanced and flow tested.
Having rebuilt 22r/e's a 7mgte and the 3.0, I would to say the 3.0 is a lot more mentally tiresome than the other 2. There is just a lot of stuff that has to be mapped out and marked before the tear down. The layout of the 3.0 also really isn't a ziplock friendly engine, I found using cardboard to hold the bolts in the order they came out w/a note of where the part goes worked well, a lot easier than ziplock bags. W/the 3.0 a digital camera is almost as important as the FSM, especially if there will be some time between tear down and the rebuild.