I have associated with and spent a lot of time in machine shops when I was younger, but haven't been keeping-up with current practices over the last 20 years or so, so it's possible (maybe even likely) that practices have changed............so take what I say with a grain of salt. Also, with today's machines and manufacturing techniques, the specs on quality internal engine parts have become consistently "dead-on". So perhaps your machinist is well within his job description to do it that way, but way back when I was involved, standard practice was to 1st have the new pistons assigned to each to a cylinder, then each cylinder was bored to precisely fit it's piston. So to me, not 1st having pistons just seems wrong.

Any time you put new rings in an engine, they should be checked and verified that the gaps are not too small. Gaps that are too big will allow small compression leaks, but that is far better than small gaps. Gaps that are too small may not allow for heat expansion and that can result in broken ring lands on the pistons, so follow the specs in the Toyota manual. FYI, Toyota changed the ring gap specs to be larger in the later years of van production, so it might not be a bad idea to go for the specs found in the 89 service manual. If you check my blogs you will find a whole section devoted to piston rings where I measure and discuss different brands of rings. Based on what I learned there, I would recommend genuine Toyota rings.

Every engine I've rebuilt or overhauled so far I've replaced the bearings. Never before have I paid attention to mark 1, 2, or 3. I just measured the crank to insure it was in spec, then got aftermarket bearings. I've had to have cranks machined undersize before, but rarely for a Toyota. In those cases I just purchased the bearings for the new size and everything was good. That's always worked out okay for me, but I've never been completely satisfied with clearances. They've always come out very close, but seems there's always at least one or 2 journals that are a tiny bit off (barely within spec or perhaps just a tiny bit outside on the "loose" side of the spec). I've never had a serious issue as a result, but I have encountered slightly low oil pressures and I blamed that on the slightly loose bearings.

I'm currently gearing up for another 4y engine rebuild, and this time I decided to use genuine Toyota bearings. This engine has never been torn down, so not knowing what bearings are in it (which mark), I ordered all possible combinations from Toyota. When I get things torn down I will be checking and replacing with precisely the same bearings Toyota originally used (it will make me feel better ).

I don't remember how much $$$ they were (purchased almost a year ago), but they were a bit expensive. I purchased most from www.toyotapartsdeal.com, but they claimed some were NLA. I ordered the "NLA" ones from another on-line Toyota parts store (slightly more expensive) and was successful.

Not sure if I'll take pics and/or document this new project because I've already done that (here and in my blogs), but I may edit and/or add to things as I see fit. Good luck with your project. Tim