Friction to index

Thinking of doing a slight upgrade to my Schwinn Cruiser. When new it was a 1 X 5 friction shift with (sub?) entry level Suntour. It shifts well, but I often ride it in traffic and would like to have it shift a bit faster and have a bit more flexibility in gearing. Sorry IGH is out too expensive for a entry level bike such as this. So I'd like to convert it to indexing either 1 X6 or 1x7. I was thinking of getting a deore six speed rear shifter ( Deore SL-MT60 ) and replacing the 5 speed freewheel with a 6 speed or an Altus [COLOR=rgba(0, 0, 0, 0.87)]Shimano M310 Shifter [/COLOR]seven such as this : Aultus 7 speed shifter pod and replace the rear freewheel with a 7-speed.. Has anyone tried this? Is it feasable??