The Epson TM88-II driver is functionally identical to the Samsung SRP-350. The two printers are identical as far as the hardware goes, as well.
The Epson TM88-II driver prints just fine to the SRP-350 with a slight loss of print quality and has the advantage of having a paper size of 80mm x 3276mm (roughly 10 feet), long enough for most receipts. The Samsung driver doesn’t have this option.

To set this up in 8-series, first uninstall the Samsung driver.
Next, install the Epson TM-88II Partial Cut driver on the correct LPT port.
Set the Windows driver paper size to “80- x 3276mm”.
In Rpro printer settings, make certain the Active printer for all receitps is the Epso TM-88II PArtial Cut and the paper size is set to “80- x 3276mm”.
Lastly, any document designs that will be printed to the SRP-350 need to have the PAGE HEIGHT set to a longer value. Set the page height to the largest number possible (999). If the document doesn’t fill up that entire length, it will cut at the end of the text properly.