Hey, the manifolds' will work. If you go to the muffler shop, have themmatch a piece of pipe to the head pipe diameter. have your oil filter in place then have them bend the pipe to clear. I'd only go 1and3/4 inch if that's correct to bend it around the filter, then go with 2&1/4 on back. I've got manifold for the 69-70 318 and it is the same as the 73-74 340 and has a 2 inch exit compared to the 2&1/4 exit on the 70 340 manifolds. I messed up on the exhaust on my 73 as I had a right angle adapter on my 73 340 motor. We pulled that motor out as it was the original (I bought the car new in Oct. '72) and did not want to mess anything up til I can overhaul it (200,000 miles). Break em in the way you want em to run. We set a 318 in for the time being and had to put adapter on as the exhaust was made for the adapter. My '71 was done with out and either oil filter will work. Have headers on it now and the straight on filter works like a dream. Allen