Getting on with build bit confused, I sourced what I was told a T140 cylinder head numbers 71-3779/2 have just purchased standard Hepolite piston kit for the same and standard barrels sourced but the valve pockets( recesses) on piston crowns are the same size whereas the inlet/ exhaust valves on said head are different size obviously? Is this a discrepancy ?? Many thanks Guys & Gals
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The number in the cylinder head isn’t the part number. It’s the cast number and although it has the same configuration - 71-****- it is not the part number. Here’s a list showing cast numbers IDs
Yours identifies as a T140E ie it has parallel ports for the carbs.
However, don’t worry, any knowing dealer would have supplied you with the correct pistons knowing the correct part numbers. The piston part number for a T140E is 71-3778 as shown in the parts catalogue and Feked’s suppliers webpage:
They certainly look like the correct pistons. The box should have their application on the sticker attached to the box.
Although I believe the original pistons are about 7:1 these pistons will give you about 8.5:1 - I’m trying to remember here so don’t hold me to that 
I’ve used many Hepolite pistons and they run fine. The valve recesses should measure the same so that they can be mounted any way round - I always have the piston top lettering (STD - standard) able to be read as though you are sitting on the bike.
If you are in any doubt then measure the diameter/chord of the valve head and then measure the piston recess. If you are still in any doubt then bolt on the head and rockers on turn the engine over slowly by hand - no sparkplugs obviously and you’ll need the pushrods in - then feel the pistons go through Top Dead Centre a few times without hitting a valve on the intake stroke.
Best of luck and let us know how you get on. 
Edit, sorry just reread your post - you say you were told the cylinder head’s part number? A 1977 T140 does not have a parallel carb head they have splayed carb heads.
For a 1977 T140 the piston part number is still the same - 71-3778 for a 7.9:1 piston and 71-3676 for a 8.6:1 piston. Both pistons are a 76mnm standard bore so any one will be fine.
I hope that’s made everything as clear as mud 
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Thanks for the great info again Bud , have checked everything and is ,as you say, was gonna do a dry build anyway , so will definately do that . Onwards and upwards !!
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