Deployment solution 6.9 SP3 upgrade to SP5 MR3

I'm looking for some info on this upgrade path. I'm currently at 6.9 SP3 and need to get to SP5 MR3, there are several versions/revisions between where I'm starting from and where I want to go.

What is the path? Can I just use the SP5 MR3 release and apply it directly onto my SP3 install? I noticed that there are WinPE updates in the SP5, SP5 MR1 & SP5 MR2 downloads, but not in the SP5 MR3 download. Can I just apply the latest WinPE updates to my SP3 install?

So many questions. . . any help here would be appreciated