I get what you’re asking, and it's true what people have said so far. But here is my two cents:
You’re asking the wrong question good sir!
I have a 2004 2120 Parker with a 150 outboard - It has one motor and a kicker. If my motor fails I could spend the next two days limp'in back in on my 9.9 kicker motor and may live. I service my motors every year professionally and I feel safe with them - I can go 30 miles off shore. I don’t.
The 24 foot boat you speak of would handle better in waves than mine. But your motor is way older. You have to ask yourself: Will this motor run for 30 miles, shut off, and start back up? Are the hoses new or from 1978? 1987? 1992? 202? 2014? What about this part or that part? Is every part new? What part will break next? Do I have tow insurance? Do I have sea tow? A good VHF radio? A life raft? What if the boat sinks? Do I have flares? The equipment that can save my life or my buddies?
Any boat can go offshore... The real question should be while offshore, when my boat is sinking, can I save myself and my buddy or will I die today. If the answer is yes I have all the gear to save our lives, the next question is why is your boat so old? Did you restore it? Are you in love with that year? Is it mint condition?
How about this question? You want an older boat to go offshore but do you have the gear to catch the fish? Have you priced offshore gear? It cost as much as the boat.
I used to think I wanted to go offshore, then I found inshore fishing was expensive and challenging enough. The back waters, the bays, the inshore fishing, block island...and more...There is a lot of ocean to cover even before going offshore. If you haven't mastered those tests...If you have to even ask the question will this boat be able to go offshore...The answer is simple...NOOOOOO!!!!! No Dude, do not buy this boat to go offshore...will it make it...yes, the first time maybe even the second or third...It's about the time when that 1 thing goes wrong...that one time...the time that you die...
For anyone who asks the question you just asked...the only answer is NO.
Hope this helps.