Jim like many of us with older MH's it is hard to know how much is to much for a repair. In your first post you called the MH "beloved" so I think you like the MH. I would spend the $1700 for the rebuilt 454, add headers, a free flow muffler, and a larger core radiator, new hoses, belts etc for less than $3000 in total if you do the work yourself. You will have a great running MH that will perform better than 90% of the brand new diesels or gas MH's out there. If you buy another used MH you will put $3000 to $5000 into it anyways to fix it up. If you buy a new MH you will lose $30,000 when you drive it off the lot. Hope this helps.