The Ted Williams branding places it in the 70's. There were two distinctly different TW 7.5s.
The earliest was a pretty slick low profile water cooled motor that was on Scott-Atwater's drawing boards when McCulloch bought them. There was also a 9 hp version. They were some of the lightest and best running in their class. You'll also find these motors with just Sears, or Elgin markings plus Scott and McCulloch. It most definitely had a fuel pump.
The second motor came after Mac folded their tents and was an aircooled powerhead with water cooling of the exhaust leg. These were built by either Eska or Clinton. Very similar and I haven't owned enough of them to know them very well. These were very minimalist motors and were rough and noisy but their simplicity attracts some followers. These usually had an onboard fuel tank and sometimes the ability to also use a remote tank. I believe the fuel pump on those was part of the carb.
A great place to ask these type questions is at AOMCI.org where there is a free forum populated by long time collectors.
