Will it fit thread

Although this isn't exactly applicable to your 74, I had a 65 Valiant I had a stock width 8 3/4 under. I put Centerline 15 x 9.5" Auto drags on the rear. I got them on there by using the MP "3/4" spring relocation kit.....it actually moves the springs in a hair over 1/2" as that's about all the room there is. BUT, that gave me way more room than I imagined. I ran a 28 x 9 x 15 MT ET Street and had room for bigger. I did however roll the inner lip of the outer wheelhouse up just in case. Of course, to use that kit or one similar, you have to relocate the spring perches. Really not a difficult job and does give some extra room. Just food for thought.