Alterations - Tapering a pair of trousers

[krudsma]

First off, apologies if this is the wrong forum for this question. I recently bought a pair of vintage trousers. Based on the cut I'd say they were from the 80s or 90s; they fit well in the waist, but they're rather roomy through the entire leg. I was hoping to taper them down myself to something a little more modern, though certainly nothing that would qualify as "slim fit." Most of my trousers have an 8.5" leg opening, but these are about 9.5". In the past I've had some success tapering from the knee down, but I've never attempted to take in excess material in the thigh. If anyone has any advice or resources pertaining to this, I'd greatly appreciate it.

Here's a very grainy, terrible photo of the trousers in question:

[posaune]

I attach a pic. It is the standard pants overlaid with a jeans pattern. You can see where you have to do the alterations under the steat line. If you have front pleats you must take it above the line in front too.
lg
posaune