I've had similar aggro on my T100c although mine is a 68 has the pipes offset and doesn't use the H piece.
If you do a search for 1970 T100c on here I'm sure you will find someone who has one or has rebuilt one and they should oblige with a detailed photo.
Depending on what parts you have already and what you need you are probably best advised trying to get everything from one supplier. I got my downpipes and mufflers from Sheffield Motorcycle Spares http://www.britbikespares.com/
although it took two goes to get the correct pipes.