You will not get a legitimate safety for that bike without turn signals. All prescribed (by CMVSS 108 ) lighting that was original-equipment has to be there and working. Doesn't necessarily have to be OEM parts, but they have to be functional equivalents. Many mechanics might choose to overlook missing reflectors (also part of CMVSS 108 ), but they would be within their rights to say no because of missing reflectors, too.
It is of no relevance that the HTA doesn't include turn signals as required equipment and it is of no relevance that you plan to use hand signals (which almost no car drivers will recognize any more). The OEM lighting (or functional and compliant equivalents) has to be in place and working.
Do you still have the parts? Switch and wiring are still in place so that they can be re-installed front and rear?
The term "bobber" sets off alarm bells. A lot of those have many more problems. License plate mounting, license plate lighting, etc.
I am sure the "bobber" community has their "go-to" guy who perhaps you need to find, but he is putting his mechanic's license at risk by doing so. I wouldn't.