Take 6 to 3 north to 128 north to 95 north.
DO NOT TAKE 93 NORTH through Boston. No propane is allowed in the tunnel. It is strictly enforced and it has been reported that the fine is huge. There are many cameras in the tunnel.
An alternate route, but much longer, is to take 6 to 28 to 25 to 495 to 95 north. It is much longer. It is a very easy route as you need to make your way along the canal to 25, then stay straight to 95.
I would take 6 to 3 etc. and plan on being at the 128/93 split well after 9:30 am and well before 2:30 pm.
Paul
EDIT
I checked Tropical Ron's data on Google Maps and it is correct, but I still would take route 3 just making sure that I was making the loop around noon.