I bought a 66 or 67 425 that was mildly built at a shop with a cam and a valve job. I plan on dropping this into a 76 cutlass supreme with a 350. The 425 came with a set of gbody headers and I was wondering if these would work or if I'd have to get a new set. I was also wondering what kind of power a 425 with a mild cam would produce. The guy I bought it from said that he was running low 13s in a 60s full sized Pontiac. Thanks in advance

 

It also came with a rebuilt th400. I think that it should drop in pretty easy I just need to get a th400 yoke and shorten my drive shaft but other than that all of this should just bolt up right?

 

G-body headers work in a G-body. Header manufacturers wouldn't waste the money to design, manufacture, and inventory different part numbers if one part number worked for both. Do you even know if these G-body headers are for a BBO or an SBO? As far as what a motor allegedly ran in another vehicle with a different weight, different rear axle ratio, different tires, and different driver, well, draw your own conclusion from that. Without knowing the details of the cam, how it was set up, what the valve size is, what the CR is, or how the engine was assembled, guessing at performance is pointless. Yes, it will drop in to a 76. You'll need to move the trans crossmember, and you will want a double hump crossmember if you don't have one now. If the TH400 came from the same car as the 425, it will be a long tail trans and it will NOT have any provision to drive a speedometer cable, as the Olds full size cars from that period drove the speedo from the left front wheel.

 

That cam is designed for the late 39 degree lifter angle. Some 425s had the early 45 degree angle and some of the cam lobes won't be in the right place, so to speak. Usually the 67 block is late angle, 66 is early, Toro with the .921 diameter lifters are late angle.