I am with those who say take it out and tear it down. That does not cost anything. Then you can start making informed decisions. And since it does not run now, you are not out anything. And I respect your desire to same money, we all do.
Re your babbitt question, if the babbitt was good when it was "parked" years ago it is probably good now. Babbitt engines do not mind being torn down. Babbitt does not rust. Babbitt will go back together easily. The thing with babbitt is clearances and fracturing. You will check those when you tear it down. No cost. Adjust if necessary, no cost. Just keep track of measurements. No cost.
I gather you have a decent tool set. Get some measuring tools, a cheap Harbor Freight micrometer is OK for a one-off job.($30) But have quality wrenches and sockets.
You have to get rid of ALL rust, otherwise the engine Will fail. Soon. This can only be done by a teardown, scrubbing, and a hot tank, or whatever the EPA allows these days. Maybe $50, even here in Calif. Check locally. Scrub all passages after the hot tank, per James above. Set of cheap Harbor Freight scrub brushes, $10.
In once sense, tar and crud in the pan may be a good thing for you, as it may be a good indicator of tar and crud elsewhere, which will protect things against rusting. Tar and crud cleanup, no cost.
Surely you need to replace the distributor and drive gear and at least some valve springs but for the cost replace them all. Check the valve stems for rust. I cannot see them well enough in the pics, but #4 and 6 seem not rusty, just cruddy. That is what wire wheels and kerosene are for. Clean them yourself, no cost.
The key will be the condition of the cylinder walls, crank journals and cam. If the cylinders are rusty, they need to be bored out, and new pistons purchased. No fudging here. $100 for the pistons, plus machinist costs. Check locally for machining cost.
Rusty crank journals need turning, and maybe new babbitt depending on the amount. That gets expensive. But good babbitt usually means good journals and that is my bet on this engine. If it turns over now, you have a fair indication babbitt and crank are not terminally damaged. But you do not know until you look. No cost.
Cam and lifters can take some pitting, but not much. Used cam and new lifters are fairly cheap. But you do not know until you look.
The block surface and head can operate with some rusting pits if they have them (not optimum or recommended and others will disagree, and I would have them surfaced) but it can be done. But even there, check with a machinist for price.
As Ross says, you may be able to do a "reasonable" rebuild for $3-400. I would up that to 5-600, even $1K if you want a Cadillac job, but hey, I am in Calif.
I would not give up on this engine yet. If you have a good block and crank, everything else can be worked out without great expense. If you are willing to spend the labor time yourself, and spend the time to learn, you can probably resurrect this engine. Model A parts are not really expensive. Most of the cost of a rebuilding is the expert labor. (And that cost is justified, I am not knocking it.) It wont be a racer, but it will be a good and reliable engine.
But the point is, you do not know until you look.
If you learn to do it yourself, you can save thousands of dollars. Get a few books, get all the parts catalogs, not only for prices but Brattons and others for their hints, join a club, search this forum (it has everything) and ask questions. This may become a project for all of us. It will take some time and energy. But it can be done, and you feel really good about doing it yourself, very satisfying.
You can have it on the road by next spring for touring.