check the compression and get back to us. Like boatman and others have said it will tell you a lot. Whenever I look at buying engine or anything with one be it a boat outboard, car, lawn mower, weed wacker, chainsaw, anything with a engine I always bring tools to remove the spark plug/s and a compression gauge. I always check the compression before buying presuming the current owner is alright with it. Most people are as long as you don't mess something up. If they aren't ok with it thats usually a sign to walk away. You can use a cheap harbor freight one they work just fine it's what I have. Like I said there good to have to check other engines on things you may buy in the future. It can save you from wasting a lot of money on a mistake. It should have close to 100psi or more in each cylinder in order to run worth a crap at all. They should be with 5psi of each other if everything is good. If they aren't close to 100psi or more than that there is a problem, and you will need to remove the head to inspect and find out what it is the problem. The head shouldn't be to hard to remove on that engine. I think the HF compression gauge is around 20-25 dollars its money well spent. It has saved me from buying lots of things that had engines that were pretty much done.
Red neck engineering- If ya can't fix it with duck tape, bailing wire, zip ties, and JB weld well than it can't be fixed.
If it moves and it aint suppose to duck tape it. If doesn't move and its suppose to put WD-40 on it.