without removing EVERYTHING from the front of the block including AC components? (68 xr7 J-code) 
On a 302 this is just a straight up pain in the butt. Be sure to note which bolt came from each location as there are about 5 different lengths and they have to go into the right place. It is also VERY common for the bolts to break off. Use lots of penetrating oil and take it easy. I will rock them in and out to make sure that they are not being twisted too hard. It is also common for you to find that some of the bolts have rusted down to a smaller diameter. I always replace those with stainless if you can find them. I also run a tap through the threads before putting it back together and add a thin film of oil on every bolt,
I recommend beer on the side an some good music to round things out…
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A 351C is not much better, but maybe some. When I changed the cam in Isabel a few weeks ago, I was able to leave the three bolts that penetrate the timing cover - but not the block - in place which meant that the pump to cover gasket was uncompromised. I put the timing cover back in place with the water pump on it and although more unwieldy, it worked out nicely.
Also, I have good things to say about Permatex Ultra Black. Apparently because I used UB as a sealent, the timing cover to block gasket came off the block clean with the exception of a little of it tore off by the two dowel pins in the block (which I found odd since there is no clamping there). When I reassembled, just a thin, new coating of the gasket with UB and I re-used it!. For perhaps the first time ever in close to 40 years of working on cars, I needed no gaskets to do a cam swap!
Getting off topic a little but I have to mention also that I did the change without removing the intake manifold! Another first. I was able to get the lifters out between spaces that the 351C factory type heads have in two places. Getting the lifters back in was another story but it still beat the heck out removing the intake!
Anyway, sorry this borders on OT, maybe there is something helpful to you in there.
I just did mine about 2 months ago and I’ll ditto “Be sure to note which bolt came from each location as there are about 5 different lengths and they have to go into the right place. It is also VERY common for the bolts to break off. Use lots of penetrating oil and take it easy. I will rock them in and out to make sure that they are not being twisted too hard” ( I had 25 ziplocks on the floor) and “I recommend beer on the side an some good music to round things out…” 
I don’t know about the 68 but I pretty much had everything off the front of my 73. 
Have a new pump ready to go in and have been putting penetrating oil on the bolts - hopefully they will all come out whole, and have ordered s-steel replacement bolt set. Someone recommended replacing the timing chain at the same time. I have a book of detailed maint records on this car; one entry at 122k (133k now) shows what looks to be “chain & cam gear, harmonic balancer”. Not sure if I depend on this meaning new timing chain or not! Do not want to replace unnecessarily but would want to be safe too…What do u guys think? THX
The note sounds like a sure sign to me.
All of cooling system a done deal and running nice and cool! Thx to all for input!