a bent valve would show on compression test. did the sparkplugs look good? easy to check for a bent pushrod. stock magnum springs are light-85lbs at 1.64" and 200lbs at 1.21"
Plug did look a bit fouled, but we were having trouble with a shitty Chinese HOLLEY regulator. swapped it out, new plugs, seems to stay clear now. It's wierd. when you pull that plug wire it dosent affect the engine as much as the others.