235 vs 261 engines

[M38CDNBill]

Hello All,

Questions for the 235 / 261 engines experts,

1) Does the camshaft is the same between 235 and 261 engines?

2) Does the hydraulic lifters requires the same camshaft that for the mechanical lifters?

3) Does the hydraulic lifters has the same length as the mechanical lifters?

4) On a 235 engine which has mechanical lifters, and pushrods which come with, may I change these mechanical lifters by hydraulic ones?

Cheers

Guy