Just needing a little help from some of those more familiar with VX.

Flying my second time with VX SEA-SFO and I was looking to do the following:

Currently booked on VX755 leaving SEA at 0945 on 16MAY. I want to change over to VX751 leaving SEA at 0700.
Once 24 hours prior hits and OLCI opens, I would buy-up to F on VX755 for $50 per seat (provided F is still open on VX755).
I would then like to change my flight to VX751, which would be free of charge because I'd have a F ticket at this point. (Provided that VX751 still has availability).

Does the above actually work as I intend it to work, or will I run into difficulties?

Thanks in advance!