get all your toys now, its a lot harder when your married and own a house
It's your $, do what you want with it. I don't know if I'd want to be tied to a house for 15-30 years of payments either.
If you're not paying cash for the Bronco build, it'll bring your income to debt ratio down. I wouldn't even think about the house until you and the SO are legal and married.
If it goes to shite and y'all don't work out, at least you'll have your bad arse bronco to go pick up more chicks. But learn to work on the Bronco too. The knowledge and satisfaction from fixing your own stuff is a good thing.
You sound like you may be like me though. I have a bad habit of dicking with things I should just leave alone and they end up running worse, or start leaking worse.