Let's see... according to Lavery, The Ship of the Line, Vol I:
Boyne class second rates (to the draught of the Victory)
Boyne and Unicorn, ordered in 1801, launched in 1810 and 1811 respectively.
Length of gun deck: 186', length of keel: 153', breadth: 51', depth in hold 22'
Armament: 28 x 32-pdr, 30 x 18-pdr, 30 x 12-pdr, QD 8x12-pdr + FC 2x12-pdr
For comparison, HMS Victory as built:
Length of gun deck: 186', length of keel: 151'3" , breadth: 52', depth in hold 21'6"
Armament: 30x42-pdr, 28x24-pdr, 30x12-pdr, QD 10x6-pdr + FC 2x6-pdr
So the vital measurements are very very nearly the same, probably handwaveable in 1:100 scale!
Armament differs a bit, primarily on the middle deck where the second rates have eighteens and the first rate has twentyfours. (The Vic had her 42-pounders replaced by 32-pounders at some point, as they were lighter, handier and fired faster.) The second rates have one less port on the lower deck and one more on the middle deck.
You will certainly see differences at bow and stern, the stern is much less raked on the newer ships as shown in the photo above. But if you want a realistic conversion option for the Victory, these two ships are as close as you get. Copies of the plans are to be had, I think via the National Maritime Museum in Greenwich. It will cost, of course.