He 'thinks it's same as a Holbay Hillman Hunter, although there's no guarantees'..... and lists it as a 1600cc engine! Looks very dodgy to me, especially as he's started at £75 no reserve, including the gearbox.
Building the 'Mark II' fastback Rapier ('Arrocuda').
I've had a look in the parts books and those carbs and that bracket look exactly Series I-IIIA parts.
So it's out of a Series Rapier (or Alpine) - the only way it could be 1725, or Holbay, is if someone fitted a 1725 into an older Series I-IIIA car.
If he's willing to remove the head and sump you can find out. If it's a 1725 it will have five main bearings, if it's got a Holbay head it will have heart shaped combustion chambers instead of bath tub shape. You might get lucky but I wouldn't bet on it.
Don't think so, looks like an earlier one to me. certainly the thermostat housing cover is the early type. I don't recognise the carbs either and the bracket reaching over the top of the rocker cover is for the air filter housing I think.