Subaru gasket. Those others and variable thickness are unnecessary.
Clean the head bolts, holes, and resurface the heads.
You don't need an engine stand. An old tire works well for holding the engine if your capable of moving it around some. Prop the tire up on wood or pavers or stone or whatever and you're golden.
"Rafters" - just don't do a point load of one or a couple points - spread the load out over as many "rafters" as possible. Lay some 2x lumber edgewise across as many rafters as you can - preferrably spreading it out over a few rafters/trusses rather than just one or two rafters and one or two points. Lay a couple 12' 2x's across 3 or 6 or whatever you can get rafters and then use that, rather than the rafters, to hoist from.
Garage "rafters" are too variable in spacing, design, loading, rafters/trusses/bottom chords, hurricane straps, tornado, local code, outside of code..and are they already loaded with storage or compromised due to age in some way... etc to comment. Ideally you have 2' spacing trusses, some "pole barn" type garages like metal siding/roofing company installed versions are 4+ spacing. Most aren't designed for any significant live or point loads like you're intending but you can get away with it just fine if you spread the load out like I said. Don't be dumb or just hook it up and go - think about it for a couple minutes, slide some boards up there and you'll be fine....I mean as fine as you can be without sending me pictures of the rafters...legal disclaimer...you might die...etc.
I designed roofing systems for my first engineering job, we specialized in complex structures.....not your typical home builders/congtractor or lowes type stuff, though i did plenty of that easy stuff as well.