The Union Graduate has a threaded outboard headstock (not sure that sound right) and a small plate which has various ways of clamping a toolpost and was specifically for bowl turning, larger bowls than would fit over the bed. It had a Left hand Thread so a chuck or faceplate could be fitted, you just had to turn with the wood rotating in the 'wrong' direction.
Hughie (also of this forum) has built his own Bowl turning lathe, big lump od fabricated steel, motor, pillow blocks to support the headstock shaft. Works very well.
Would your idea work, yes, but...
Half Horsepower motor is not very strong, Clark lathes are cheap Chinese so the headstock bearings might be a bit worn or likely to wear out fast under heavy pressure.
How are you going to support the toolpost if the head hangs over the bench. You'll be putting a fair amount of down pressure on it with the tool engaged with the timber.
There are all sorts of things to take into account and you'll excuse me, but Safety is not just one of them, it's the Main One of them.
