4.108 Oil Leaks and Engine Gasket Sealants

[phorvati]

I am about to start putting my westerbeke back together after head, block and crank were at the machine shop for testing, etc.
Its w40, based on 4-108 block.
What sealants are recommended during assembly?
Locktite574 is expensive is it worth the price?
I also plan on getting Foley Engines rear oil seal kit, any experience with those?
What about using Napa Form-a-gasket sealant?

I am hoping that if this is done right, i could be oil-leak free. So any recommendations would be appreciated, particularly any areas that need special attention during assembly keeping the oil leaks in mind.
Thanks