Judging by the rust on all those parts, i would say that's a hard no. The carb could be a knock off, and i got a new one on eBay for $13, that included the air filter. It has an adapter though, so the carbs is probably the only thing that i would consider buying. Heck its only $25, but you would end up with half of it being junk, maybe a little elbow grease and some checking you might find a gem in there, or you might just toss it.
As for the predator, it might not be a bad idea to get it for the top plate and flywheel cost. Again, used race engines could be complete junk, or you might get lucky. There is always a reason why someone wants to get rid of a race engine. I personally would never consider selling any of my race engines. Somone that wants to sell it might want to sell it because they are getting out of the sport (good), suck at racing (good), are broke (good), or because they ruined the engine (bad), or wore it out (bad), or just couldnt win because the engine performs poorly because they ruined it and dont know why (bad).
See what i am saying? even the flywheel could be messed up. Could have lapped it too long and wore out the taper, or spun the flywheel, or had it on an engine that blew up before.
Just do your due diligence, and know that value is dependent on how much you are willing to pay for it. I have been on both sides of the negotiation and can tell you that when im ready to sell something and someone shows up with $100, thjen offers me $80, im like ahh heck why not you scumbag. Other times ive stuck to my guns and said nah, take it or leave it. There is always room to negotiate, even if you showed up with less money.