I had swapped jdm(japanese domestic market) low miles engines in 2 nissan nx2000, let me tell you 4cylinders are pretty easy to swap, as long as you label it yourself and follow haynes manual, and have a dad to help you. v6 might be a little challenging and time consuming.
Now you should look on the internet and find good company closed to you, ship it to a business address and not you home since you will pay more shipping.
jdm engine usually have different egr systems and you will need to swap that over.
if you are going to let someone else do it labor might cost you ~$800 since its a v6 3.0l
and a lot of hoses to disconnect.
if i had extra money i would buy new jdm auto transmission depends on your miles and condition... B) the tranny is only ~$400 extra
The labor price your mechanic offeres is very, very cheap so go with it.
your car is 93 so if you are putting 93 engine ~$550 plus shipping ~100 on ebay and 30 day warranty, try find a reliable company like soko
http://www.soko.com/ (the prices are probably in the 900 range but you get quality product with warranty)
and i bought mine from alljapaneseengines in florida.
i would try to put the latest year possible with like vv-t search around if someone else did it, you will probably need to get new wiring harness and ecu(computer). if you get 93 all you have to worry about is egr. and sometimes different header, just swap yours over.
look it up to see whats best for you budjet