360 308 casting heads info needed

[gunmetal]

I took some advice that 308 heads were the best stock heads you can buy, maybe so but what someone forgot to mention is that they are a very thin casting and are prone to cracking.  I bought a set of remanufactured heads thinking I was good to go, new valves some port work and I'd be ahead of the game.  Well I got the heads starting porting them and was told that they had been "plugged"? between the intake and exhaust on two cylinders (both heads).  Now I've got time invested in the heads and am afraid I've just wasted my money.  Can anyone give me some advice on taking these and having 2.02 valve put in. I've attached a couple terrible photos, I know they would need a vavle job but have been told that theres a chance the valve job could open the repair. 

Anyone got two cents to add on this?

[Chryco Psycho]

plugging the heads between the valves is a normal repair & will not cause a problem  , even if you install 1.94 valves the heads flow very well

[gunmetal]

My thought was that if I could use them that I would put 2.02 valves on the intake side.  Stupid question maybe but how hot do the heads have to get to crack them, my motor heated up to about 200 once (not with these heads on) because of timing.  Fixed that and it run about 195 all the time.  Does NOS affect heat of the heads in any way?  100 shot.

[Chryco Psycho]

the 308 heads are problematic with the cracking between the seats but repaired they are fine , once cracked they will not recrack with heat . never used Nitrous oxide so no clue , the NOS set up properly should drop the combustion temp not raise it though

[Aussie Challenger]

It is a poor pic but it looks like the valves have sunk down some, who was supposed to have remanufactured them?