Wheel Recommendations

[DDYTDY]

Greetings,

I have a 1989 Caprice wagon I've build to pass tech to 175mph.  I'm having trouble figuring out what wheels to get for it. I need 17X8 5X5bcd with a 4.5" backspace.

I bought Weld Laguna's but the 60 degree lugs are a no-go if I'm reading Loring Timing Association's rule book right.   A friend suggests steel smoothies but I'm not finding anything rated for anything over "highway speed"

I'm open to 15" wheels but cant find a 275/60/15 with better than a T speed rating. I want to keep a 28" tire in the back.

TIA