If you are definitely going to get a looser converter then you have more choices. From what you described as your parts if you get a converter that stalls from say 1800-2200 you could run the 268, 270, 276, or even the 280. All 4 of them call for a stall between 1800 and 2200 and at least 3.42 rear axle ratio which you already have with 3.55's. The compression ratio on your stock 5.9 is factory advertised at 9.1 to 1(depending on the year). The problem with that however is that what the factory advertises the CR to be and in actuality is probably a whole different story. I wouldn't be surprised if your pistons were .050 down in the hole and you actual compression is actually 8 to 1 or maybe even less. I have found best success when you have unknowns or "unsures" or borderline specs necessary to run a particular cam that using a little less camshaft than what "desktop dynos" call for as a maximum cam is a good bet.. . If it were mine I would probably run the 270 or 276 if you get a converter that will flash to 2000. Of course the higher you stall will lend itself to the 279 or 286. If your definitely getting a higher stall converter then you can always put more cam in there till you put the converter in there. But then youre back to the limiting factor with the CR, I wouldn't bank on youre having a true 9.1 to 1, so that would put you down to the 270-280 range. But you can measure everything when you pull the heads and mill the heads to achieve the compression ratio you want. I don't know what the combustion chamber volume is on the heads you are getting but i'm sure that you can make a situation to raise it . But, now were spending even more money, .All these cams are running an LSA of 112 which will definitely take some of the lopiness out of the camshaft. However not all is lost with that. I did a bunch of research on what cam to run with nitrous. It seemed that the more I read the most common specification that was common to most advertised "nitrous cams" was a lobe seperation angle of 112-114 degrees. So your cam might not have that heavy lope and sound very "cammy" but you will make more power on the 112 LSA than one with say a 106-108 LSA. If you currently have a 904 and want to get out of this absolutely cheap until you acquire and build an A500, you can get a slant 6 converter (72-80 had 27 spline input shaft and 27 spline slant 6 904 converters are plentiful and cheap) and install it behind your V8 904 and achieve an 1800 to 2000 stall speed. There have been so many free slant 6 engines and slant 6 trannies advertised here that you can probably get someone to give you one if you pay shipping. Hell, I have one I would give you but it is out of my 70 and has different number of input splines. Do not need new pushrods or lifters.
