I don't believe there's any differences in the actions between any of the models - if you wanted an action to start your own build, might as well buy the scout, which is the least expensive version I've seen listed anywhere. You might be able to peddle the youth model Scout stock online to recoup part of your investment...
I've still got the OEM bbl that I removed from my Varmint MTR when I re-barreled it with a Shilen. I just ordered a VPT w/Manners stock, in the 24" bbl version; have no intention of keeping the bbl length at 24". Will shoot it before making any modifications, as I've got some very good lots of SK Std+, Rifle Match, Pistol Match, and LR Match. If that 24" bbl isn't a hammer, the MTR bbl will get installed & tested. If that doesn't turn out well, I've got a Bartlein blank ordered, but it won't be here for probably 4 months. I'd have preferred to buy the 20.5" version of the VPT, but knowing there was a good chance I'd wind up using a custom bbl on it anyway, it really didn't make much difference which bbl I got. Don't have any real use for the 16.5" version, so waited until Lipsey's got a shipment of the 24s in. This was the least expensive & quickest way for me to get into the Manners stock, even with getting a dealer's discount on them.