73 318 will J heads work???
I safely sprayed 125 hp shot of NOS with my old bone stock 68 318 and it loved it . it turned it in to a lil monster ! With never a problem. and I sprayed the dookie out it :) its tounge was hangin out up stairs so I kept the shift points low ... around 5200 to 5400
getting the pressure up with the spray and the J's will work nice but, it will be a little lazy down low off the spray. being a stock piston combo then the max would only be 125hp of spray safely. So, I do not really see much benefit by bolting on the J's . you could toss in a nice set of pistons ( expensive ) then maybe hit it with a 250 shot ? using the J's ..... humm..... getting into the land of trashed and expensive parts. but it would pretty amazing to see a 318 all setup for that kind of spraying just to see what it could do.
My point is........
you can make very good power with a stock combination with spray if you keep fat and happy, lower your shift point and take some timing out.
with a little homework and common sense, a solid stock build will work very nice with little sauce. the power is there when you need it in a bottle in the trunk. if I was going to build a 318 I would do a little more than stock cam and some mild port work on the heads. yes I would use the small heads but, that is my personal choice. just because I drive on the street as much as I can in the summer.
I have been sorta planning the my next build for my pickup and I am thinking along this combination . but, with a 360. a small just over stock 318 cam and the small heads with the small 2bb 318 intake/carb.
should make a ton of bottom and get pretty decent milage in the old Ram 150 with a 3.21
I have a set of J heads on my 360 that have had some work done to them and I have to say that I really enjoy my 360 on motor. the 360 on spray is awesome !
The 318 was even a bit more fun just because it was sneaky to have it on the spray and it was pretty close to my 360 when I run it on motor.
When I would go and tear off a 13:80 pass on street tires and a 2.76 gear I would laugh my butt off ! was just fun :)
I will be upgrading heads soon with a set of E heads and a cam change my goal is to get into the mid to low 11's and have a totally streetable combination.
There is a ton of good info here on FABO it all boils down to what ya want to do with your stuff. we all have tried different stuff and had success and failures. it is great to have all of this information to draw on. back in the old days I would have saved a lot of cash and good parts if I would have had this great resource to draw from.
good luck :)