That one is a 1970's 'Tractor-x', where x was the horsepower rating of the original engine. The power options were 5, 8, 10 and 11hp.
There were 'VE' [electric start] and 'VR' [recoil start] variants for all except the 8hp, which was recoil only.
Yours is a VR, as there is no battery compartment located below the steering wheel, or provision for one.
As you say, indications are that it was originally B&S powered, as this series all were. It's from early in the series, going by the cast alloy seat, which was a legacy from the first Greenfield model, the HD-5/8 series.
A downloadable parts list is
HERE ; see if some of those belt/blade numbers match yours.
