Who needs an engine hoist....
I did one motor swap using a backhoe and two using a skid steer loader now...
Of course, I happen to have a skid steer loader sitting in the driveway all the time, lol.
I don't trust any of the new lumber, most of what you get has growth rings with 1/4" or more between them - that does not equal strength at all. If you really want to go the I-beam approach, if you do enough scrounging work you can usually come up with one that was cut too short for a job and is being scrapped or one that is in something being torn apart. It used to be easier to find them this way before scrap prices went up, but with enough looking they can still be had. Add a beam trolley and hoist to get a moveable lift. Or if you really want to do it up, put a beam on either side of the shop and one across the middle on rollers like a big overhead crane.