Re: 8n with a 72\" finish mower
According to the I&T service manual, which has its info from the nebraska tests. The 8n has 27.x belt hp.. and about 23.x pto hp. 9n and 2n tractors have a fraction less hp, due to a lower compression ratio ( 6:1 9/2n 6.5:1 8n ).
Lots of people run 6' finish mowers on there N's. Some like 5's if their lift is weak. If you are getting too much of a bit on the 6' swath.. just cut 5' or 5.5'
Soundguy