Yup you can, I have seen the problem too if you have an old motor and take the bracket off, sometimes the seal is so old and set that it'll stay put, but if you put a new one in then it'll pop out almost every time.
Yes you can do it with the head still installed. The old bracket took two 12mm bolts (socket size not thread size) and if I remember correctly were an inch and a half to an inch and a quarter long. There's not that much room between the head and the firewall there but you should be able to feel the two bolt holes back there.
Thread is 8.0 x 1.25mm. Just make sure that the bolts are not too long (too long will crack stuff if you tighten up fully, must be at least a hair of space under the end of all bolts). So shorter bolt way better than too-long.
Of course one can essentially "shorten" a bolt by either hacksawing off the end or putting spacer washers under the bolt head.
Perfect. Thanks guys. I have a huge selection of bolts here at work. Ill make a plate and slap it on. Hopefully this solves my problem. Im working on gathering all the parts n do a 350 swap but in the meantime its my DD so my good truck sits.
Bumping. What is the part number for a rear cam seal its vaguevague. I see a felpro that is three pieces. Is that what I want and will do the front as well