Never tried it on the Savage, but when I had my old Guzzi it had 3.25x18 front and 3.50x18 rear.

So, when the time came to change the tires, I considered a 3.50 front and 4.00 rear...
...4.00 rear just wouldn't fit, chassis too narrow  , and 3.50 front too wide, wouldn't clear the brake caliper ...

So I just undid the brake caliper, fitted the fatter front tire, and redid the brake caliper up.

Handling was MUCH improved !!!  

Considering the speedo drive if off the rear tire (correction, it's off the gearbox) whatever front tire you fit will not change the speedo reading.

Now, the point is, what's the imperial equivalent to 110/90x19? Sounds like 3.25-3.50x189 to me...

I would consider a 3.50x18 to start with, so that the extra rubber compensates the inch you lose in the rim.
I'm afraid they don't make a 3.75 tire... 4.00x18 might prove too fat to clear the forks.