66 dart cooling fan

Finally getting closer to firing up the 66 - Long road Ive been on getting to this point.

Been debating about whether to use a flex fan or a clutch fan on the 66. Motor is a warmed over 318 (now 328) about 300-350 hp. Radiator is being recored to a higher efficiency unit, and I have the stock shroud that matches it. I measured the opening in the shroud and it looks like an 18inch fan should fit - however, the service manual calls for no fans larger than 17inches in diameter with or without a shroud. I already have a good used 18 inch flex fan. A little concerned about using the 18inch flex fan since the manual calls for a smaller fan and also concerned about using a flex fan - period, heard bad things about the blades flying off if over-reved.

I started looking around for a 17" 7 blade stock mopar clutch fan and have had little luck. I am now thinking of using an aftermarket clutch fan - there are 17inch 6 blade units available. Anyone used a clutch fan from flex a lite, Derale or others ?

Opinions and advice appreciated !