I just did this and used yellow freight www.yrc.com "terminal to terminal"
The freight class is 85 and the shipping weight on a half size pallet was 300 pounds. My engine had a clutch and intake manifold installed, but no exhaust manifold or starter.
They also have a First-Time Shipper discount of 60% -- if you call them at 800-610-6500 with the zipcode of where it is, where you will pick it up, the approximate dimensions and weight, they will give you a quote over the phone. (or you can do it online) Beware, they might try to add a delivery notification fee, ask them to waive it since you will track the arrival online.
The only kicker is that your seller would need to be able to build a wooden box or a stand to strap and wrap to a pallet AND have the means to get it to the terminal, and you would need something to haul it on when it arrives (they will load it on your vehicle with a forklift) If you need pickup and delivery with gate service--it will cost you bigtime.
if you are willing to roll the dice and need door to door, try uship.com.
Good Luck!