Is the 243 head a ls6 head? It should have ls6 springs right.

 

243 are ls6 heads- correct and should have ls6 springs on them.

 

the 243 came on ls6, ls2, and new model 5.3s

 

LS6 Heads ( C5 Z06 ) have hollow steam valves and better spings ( up to 575 lift if I 'am not mistaken , while 243's ( LS2 ) style have your regular steel valves and 550 lift springs I THINK.

 

If you have the 243 heads it should be casted on the heads first off. The springs are Blue not yellow like many people tend to think. The springs are rated to 575 lift but if your pulled the heads minus well get some good springs on there. Any one can tell you that the heads have "30K miles it was a garage queen..."
1. you don't know what was done to that car
2. how it was driven and what the heads had to deal with
3. was the guy good on oil changes and maintenance keeping good clean lube on those heads
4. Just get some new springs rated at or about 650 and if you have a stock cam when you do your new cam you wont have to do new springs.

 

^^^Amen to that.

 

They were free, and never used. Someone I knew bought a set of them and took the springs off.