A few 383 re-assembly questions

Please cut me some slack for asking what might seem like very basic questions;
I've been away for many years and expect some things have changed for the better.
i'm installing new lifters on an existing cam. One lifter failed and rather than just replacing one, I am replacing all.

While doing so, I'm not going to do anything other than a cursory clean-up of the intake manifold, valley pan, heads, etc because the engine is in a 32k mile "survivor" and I want to keep the mostly original look, including original paint and flaws.

1) I've cleaned the valley pan around the sealing surfaces and checked to make sure it is not cracked anywhere. I'm planning on re-using it. Any real reason not to if the sealing surfaces are good?

2) What gasket sealant is the hot setup to seal between the valley pan and the head surface, if any?

3) I've done a visual inspection of the rocker arms and shafts. I don't see evidence of abnormal wear / galling / damage. Is there anything else I should check before reassembly?

4) Why are the rocker shaft to cylinder head fasteners different lengths? Is it for oiling?

When reassembling, i'll use assembly lube, oil the other bits, pre-oil with a shaft and drill before startup and break the lifters in per manuf instructions.

Thanks

Craig