Personally I'd never go with a reman for a Ford modular. Even from the best re-builders I seen them fail. I once witnessed Jasper fail twice in a row, - it took 3 engines to get a good one.
Granted, some have had good luck with them, but I've seen more failures with remans in the past vs used. In fact I have yet to see a used engine fail since they are tested before the sale and you can test them yourself with a simple compresion test before purchase.
Yea, some re-manufactures offer more threads in the heads. It's a selling ploy that has become popular because so many go for it. So why not take advantage of the consumer, - somebody will if they don't. Anyway that's the true thought about it and it's nothing more than that.
The so called problem with the lack of plug chamber threads wasn't the the problem as this was decided in a court of law. The problem was lack of torque...plain, simple and proved. Nothing more but exaggeration since some or perhaps even most enjoy pointing the finger, - specially at the manufacturer for their own satisfaction. Sad really...
Anyway, apollumi, -do what your most comfortable with, IMO and personally - I would do this much differently as I know I would be getting much more for my money with possibly a lot less hassle. It could go both ways yes, but there's so much you can do to prevent getting a bad used engine. That is worth learning to your benefit all around.
Good Luck Man