Doesn't get up to temp in cool weather.

I feel like I'm hogging all of "Shop Talk" lately, but I am trying to get a bunch of issues resolved. 1987 L98 350 TPI, bored .030" over with stock heads and a 180° stat. Cam is a Chevy experimental with .603" lift and that's all I know about the cam. When driving on the road temp in this current 60° to 70° ambient the gauge stays in the 150-160° range. When I stop or start a climb it'll get up to temp. I've tried other thermostats with no substantial change. Suggestions? I'm hesitant to plug the bypass hole in the thermostat.

What are you using for thermostats? The 7 or 8 dollar Poppet Style?

I prefer these - https://www.jegs.com/p/Milodon/Milod...62929/10002/-1
The sleeve type will perform more evenly and outflow the poppet style. But it costs more too.

I'd definitely run a 180 deg thermostat at a minimum. If the rest of the cooling system is up to snuff, you should have no problems. If you find the temp crawls higher when stopped but settles back down when driving along, then you most likely need a shroud around your fan(s). HTH.

under edit. don't change the bypass.