I've been looking at Indian Petter types types for a while now here's a quick run down....
Indian Petters are based on the AV*** series of engines. The first Indian Petter was a clone of the AVA-1 starting in 1949 at Kirolskar. AVA-2 and larger Petters began in the 50's.
English production of the AV*** series is seems to have ended in late 60's, but durring the 20 years they were produced the different series started stopped and restated eg AVA-2 series III.
Indian Petters have evolved with TBRs and bushed types, piston oil pumps, gear type pumps heavy and light fly wheel combo, air cooled, ax air cool, water cooled, water with pumps, alternators and even electric start.
Singles and twins are common and it looks like India made a triple too. Most have a bypass filter for oil in the crank case some have an external spin on filter.
The displacement of the Indian Petters has increased over the years mostly due to longer stroke cranks and there are bore and cranks variations that Petter never built giving rise to large 13.5 Hp singles and small 12 Hp twins.
Quality ? ask Sid and the other owners, I don't own one but I know they are a big seller in the midle east and asia.
Doug