Hi Nourish
If you desire a 3 figure speed ?
In my opinion you will need a 357 cam, 8.25:1 pistons and a head with the SR sized inlet valves ( I would go alloy)
You will need NEW rods ( old ones cannot be trusted at this age), New oil pump too
and have the lot dynamically balanced
The new rods are different weights to the originals, As you are in USA, MAP rods are probably your best bet
On 23/43 and 19/42 gearing with a 100/90 x19 tyre my SR revs to near enough 4000 revs at 70 mph
thats 5700 revs at 100mph, I think standard safe revs is 6200/6500
My engine/bike is extremely flexible and will tootle along at low revs in top gear if desired Or
It will rev like a bast*&d and go like stink when desired
HTH
John