I just completed a similar job. I first tried oven
cleaner to remove the old painted name. Didn''t make a dent! Then used marine version of peel-away which took off about 80% but the remainder I had to employ 220 3M pad to remove. Once clean, I noticed the old lettering (including the previous one from the early 90s) raised the gelcoat underneath the names and had a slightly yellow shadow.
As per suggestions from other board members, I left the stern in the sun for several months prior to application of new name to bleach out the yellow a bit. That worked OK. Then compounded with 3M followed by Finesse polish to help fill in some of the abrasive marks left by the 220 (took 3 coats). Then two weeks ago applied a vinyl name, which conformed nicely to the "bumps" left by the old lettering. Finally, waxed the stern. It all came out fairly good, considering its a 1980 hull that has lost some of its luster.