ideas for Vortec two-piece rear main block 350

[Mike - 76 k20]

I need some ideas for a 350 rebuild. I'm sold on the cast-iron Vortec heads, so that's decided already. They are 62cc, I've read, and I am looking for a CR around 8.5 so I can run 87 octane.
Is that the highest CR I can run on 87? Gas is so expensive these days, so I don;t want to have to buy booster, 89, 92 (gasp), or have to *aquire* more av-gas.
I'm needing low-end torque, so I'm seeing the Edelbrock 180 degree #7101. I already have a #1406 650 carb.
Next question is - what about a 383? Speed-O-Motive sells a budget 383 kit for pretty cheap. It's a new cast crank, refurb 5.7 rods, and new pistons. I'm not planning on a nitrous bottle or a blower, so cast should be fine.
I'd then have to buy an external balancer and a 400 flywheel, right? Where is a good place to get these? I have a manual tranny.
Also, I have a choice fo two blocks, both two-piece rear main.
One is a 1973 two-bolt. It is already pulled and sitting in the back of my truck, needs to be disassmebled and, of course, to have the machine work done.
The other is a 1980 (or 1979) four bolt, currently in the truck I am driving. It has low oil pressure (I think the bearings are pretty worn) and needs to be pulled in the next year or so anyway because it's on its last legs. The problem with using this engine is that I would then have to install the 2-bolt in its place until I get the 383 built, which is probably going to be many molnths of working on it, a little here, a little there, as money and time makes itself available.
How much of an advantage is a four bolt block? Enough to justify the extra labor (and rental time with a engine hoist) to pluck it and install the 2bolt?

I'm looking at the COmp Cams 286 4x4 cam. I think it would work well with the engine setup.
What about the distributor? I have a 76 HEI, works fine, but I've never run a new one so maybe it is missing a little oomph? Even if I go buy a Summit or MSD new one, what about the advance curve? I've heard of people having a shop tune these, but where do you get it done? I live in Houston and haven;t seen anyone offer this service.
I'm full of questions ain't I?
ANother question - what machine work is mandatory? Obviously hone the bores to whatever the next size is. Deck the block. WHat about align-honing the crank? What else? I plan on this engine running strong for 100K+ miles, so reliability is key.
What about the valvetrain? The Vortec heads come assembled from GM, and the Comp Cams kit comes with new lifters, what else do I need for a complete valve-train?
--Mike