Do you want a race carb or something with a choke so you can drive it in colder weather? If you want a race carb I'd probably go with a QuckFuel 750 DP. I'm guessing your engine makes about 500 to 550 hp so a 750 carb will be adequate. For street driving a slightly smaller carb will work better than a bigger carb. If you are drag racing only then maybe buy another 850 if you want but my guess is that you'll be happier with a 750. Holley has the new Ultra XP carbs which are really nice but they are expensive. They are very good carbs though and should run great right out of the box. $1000 and they are in stock: https://www.summitracing.com/parts/hly-0-80803bkx