The intake should live with that tiny crack only at the flange--if it were split in the center of the exhaust passages it could have created grief..
Your engine sounds great..good job!..
I only pulled one head off a 305 I had in a '71 K1500 way back in 1987,to replace a burnt valve and I was sore for weeks after..I was 29 then!...
I doubt I could pull a head off "in the truck" today at nearly 57..
(and that motor smoked like a tire fire after one head having a quickie valve lapping--ended up having to yank it out and swap in a 350 I bought for it for 150 bucks that was low mileage and ran nice--should have done that in the first place!)..
I used to be able to yank a good motor out of a square body in about 2 hrs,and swap it into another truck that had the motor out already ,and have it driveable by suppertime..that feat would take me a week or more now,if I could do it at all...last "major" job I did about 10 years ago was swapping a 350 in place of a 250 six in a '79 Bonanza and it took me a week,thought I was going to be in traction after it was done..I was in agony for months afterwards..
I have been pretty lucky so far as head gaskets,I hope I wont jinx myself by saying I haven't had to replace any yet--but I wouldn't be surprised if one does s*** the bed on my 6.2's and my '73 307 in my van,that still has the steel shim originals and now that I let it sit since 2003 and only fire it up once or twice a year to move it..
If they blow a head gasket,it'll likely be the end of the trucks,I really dont feel like putting that much labor into any of them now that they are all rusty everywhere..probably couldn't buy a carbed engine around here any more either..it was hard enough finding one 10 years ago..