Heplex 11341 piston

[Greenfield]

I've just removed the piston from my 1950 B33. It's a heplex 11341 with maximum skirt diameter around 86.4mm. There are no markings to indicate whether it is standard, +20, +40 etc and would like to fit new rings.
Does anyone know what size it's likely to be?
Can anyone suggest where I might obtain some rings?
And when I reassemble, should the split in the skirt be at the front or back, or doesn't it matter (it was facing the front)?
Cheers

[rhyatt]

my go-to place is Cox and Turner at Tintinhull near Yeovil - loods of rings and pistons and rebores/regrinds on classic vehicle

chap to ask for is Kit

sorry , I cannot answer the other part of your question

[Derek996]

I'm not sure about the split skirt but the smaller valve cutaway goes to the exhaust side. I can't see from your picture if the cutaways are different sizes though.
With an 86.4m max dia it is more than  +40

[JulianS]

The split goes to the front. It does matter.

11341 is a 6.8 compression piston. See below page from old Hepolite catalogue

The oversize should be stamped on the piston top if you carefully clear the carbon.

[Greenfield]

Many thanks for your help. Having polished the piston top to within an inch of its life and with the sun now shining, under the very clear 11431 was a faint 'Made in England', under that was +060 and under that was 'Front'. I phoned Drags for some parts and enquired about the rings and they had one set in stock; so now ordered. I'll be replacing the small end bush while I'm in as I found a small amount of play.
Re the valve cutouts, they're the same size on this piston.
Cheers