only problem is he said he wanted to leave it pretty much stock and the 300 is way to long to put into a Maverick Engine bay and get any kind of Stock appearance. If he was going to go with a 300 he would be better of with the 302. There are plenty of go fast add ons and upgrades for the 250. In fact there are 250's out there running in the 12's and better consistantly. All depends on how much $$$ you have to spend.
I'd like to build a turbo 250ci just for the hell of it... classic inlines has an aluminum head now...
I have a 4.0 250cu inline six also ... original with airconditioning ... thinking of the add ons also ....
Lot of information and like the one comment stated....I am ging to keep her mostly original, that is the 250 that she came with.....hell if I was going to swap engines (which I am not), rather than the 300 I would go with the 302. Anyway, so many add ons and things you can do to these 250 in lines....some great web sites. Nothing is going to happen until this winter when she gets put away. Enjoying driving her the way she is. Later