"The 30-06 case neck did size up to 35 cal but it didn't change the body shape, it's now a 35 Whelen."
Yep, that's sorta the first step. Your press is plenty strong, I used to do it on a Lyman Spar-T and it's not as strong as yours but the old single toggle presses do put a LOT of stress on the bench.
Now remove the decapping rod, screw the .358 die down to the shell holder, lube the .35 Whelen good and push it fully into the die. Cut off the extra neck, trim it square and run it back over the expander. Then turn the neck until it's a thin as you want it to be. Anneal the neck and you will be ready to load some .358 stuff.