A replacement engine (used) is a crap shoot. You can find one for a few hundred dollars at junk yards, but there's no way to know the absolute condition of it. A rebuild can be a short block (block, crankshaft, rods, pistons, rings, bearings) purchased from a remanufacturer in combination with your present heads, manifolds, oil pan, etc. plus accessories and brackets and add a new oil pump and gasket set. Or, it can be a long block that includes the heads - all the way up to having the local mechanic rebuild your present engine and repair/replace everything needed. I have found that the fewer people that are involved in something, the less finger-pointing there is when something goes wrong. You would want to make certain you're dealing with a reputable shop and that you have a good warranty.

I wouldn't know where to find a new replacement engine. There are used low mileage takeouts from Japan (probably around $1000), local takeouts that can be bought from many wrecking yards or found through this locater:

web page

There are DIY yards that sell a complete engine for about $200 (including warranty). In this case, you would have to remove the engine yourself or pay someone to do it for you. Warranties on used engines don't guarantee that the engine is good - it means that if you find that it isn't good, you can swap it for another..... which means you may have to remove and replace the engine a second - or third - time..... expensive if a shop is doing the work.

I think the only way I would allow a shop to install a used engine is if they guaranteed it would cost no more than $2000, have no quirks and used no more than 1 qt of oil every 3000 miles.... to be replaced at shop expense until I was satisfied - and I doubt any shop would accept that deal.

I hate to estimate the cost of a full rebuild, because the term means different things to different folks. It could run from $1500 to $4000, depending on how much work is needed, how much is actually done, what rate the shop charges and the type of warranty.

Gaskets and parts are expensive through a dealer, but are of excellent quality.... particularly the gaskets. Otherwise, there are cheap parts on ebay and at most auto stores. NAPA stores usually are a good trade-off between price and quality for rebuild parts.

A rebuild should take about a week or so for a good shop. Removing the engine, disassembliy and examining the parts will take a day, a couple of days for the machine shop, reassembly and installation another couple of days. If aftermarket parts are used, I suspect you can get it done for about $2500 or so.

If you lived a bit closer, I could help - I have an extra block, crankshaft and set of heads here, but I'm as slow as a turtle.

Frank