One angle to consider is whether or not you can run this business in a manner that at some point you & the wife can cut back your hours / take some time off. You most likely won't ever be able to be 100% hands off and it may even take you a few years to get to the point where you're just putting in a standard 40 hour week (instead of 60).
Also, is it an industry that could be wiped out by technology at some point? I'm pretty sure this isn't you but I'm thinking something like a video rental store. That's something that won't even exist in 10 years (or sooner).
Does the business have an honest chance to expand if managed correctly?
I'm assuming you'll need staff of some kind. Staff is one of the hardest parts of any small business. Is there enough profit in the business to pay for quality (low headache) staff?
Underestimate income by 10% and over estimate expenses by 20%. If the numbers still work with those factors then it's probably worth a close look.
"Masked Bandit is a gateway drug for frugal spending." - Unknown303