Another gearing question

I have a 80 classic bottom end and tranny in my Z. I have a 16 inch rear wheel. I got a 16 in mag I want to use and have a new 38 tooth sprocket I am thinking of using. I think the ratios are different for the newer motor trans than the Z1's? Using www.gearingcommander.com/ I cannot find my motor. Is the 79 A-3 the same ratio?

If so the chart claims I will be doing 68 @4800 rpm to my current 73 mph.I don't ride the bike alot but when I do it is on the highway at about 70 to 75. Will this be hard on the motor? Mileage isn't a concern because I don't put many mile s on it in a season.

Wayne

79-80 LTDs with the 16 in. rear Mags, came stock with 33 tooth rear sprockets, I do a lot of high way driving myself, so I went to a 32 tooth rear sprocket, & at 70 MPH I'm doing about 4000 RPMs, I don't think the gearing is much different on a Z1 Classic,...maybe someone will chime in, but I think 38 is too big for a lot off high way driving IMO
Pete