Sure, why not? The different head could be anything except an early 273 since it's all bolted on and working. The head could be a 318 head for all we know. While this is a big mismatch, it'll work.
When you pull the intake off, take a small mirror and look under the center of the head where the numbers are. Then you'll be able to look them up and know what they are. However, they also could have been up graded 360 heads w/2.02s. Head gaskets (Pair) are about $40. Give or take.
2 my 340 intake has a much smaller bypass hose than the original intake,whats the best way to fix? don't plan to open up the motor anymore than the intake.
The earlier by pass hoses were a smaller diameter. It is possible to ethier clamp the larger one tightly or good luck in removing the old one in favor to install a larger one. They tend to rust in place.
3 will this motor work ok in my 69 valiant with the 4 barell intake? just kinda curious at this point,running on a tight budjet and am happy to have a running 360. any input would b appreciated thanks.