I have one in my 70 challenger, with 235 60 15s on the front. parking isn't that bad and those know me know im not a big guy

Mines not super fast, 6,94 in the 1/8th. Now the track isnt the smoothest either(Magnolia Dragway) but after the change I basically just pointed and went. Before I was holding on w/both hands and I swear my butt had a pucker hold on the seat as well. Lol
The Flaming River piece is a nice unit it just wasnt right for me. I had talked w/several others at the track that had tried the faster ratio units and none seemed to like them on the strip. They were all much faster than me and honestly I didnt figure at the speeds I was running I would have had an issue.

If it was me I'd get a stock box and have FirmFeel Inc. rebuild it. If you are weary of the 16:1 being a bear (I have one with 15x4" front wheels, it's not IMO) you can have them go 20:1.

I'd rather have an aluminum box any day over the cast iron Flaming River unit.

Addressing the person who described their 16:1 box as "twitchy":

I can completely understand how going from 5.5 turns lock to lock to 3.5 would make the car feel jumpy with out turning the wheel much. I have to re-train my brain in my four speed car not to yank the wheel when power shifting because it tried to change lanes the first attempt out of the shop lol.

As always it depends on lots of things including how used to manual steering you are. For instance on a day when my tendonitous (tennis elbow) is bothering my 16:1 manual steering sure seems 100x worse than a day when I remembered to take my vitamin supplements. The story here is take your meds/vitamins so you can drive a higher performing car lol.

Good luck with whatever you decided OP!