I do hope you found due and ample compensation for your poor old dad - MY son could not count on me for that kind of exercise, unless WELL made up for! Best might actually be to tell all and sundry that without his sound recommendations, you could never have managed.

30lbft torque is just a little beyond when the resistance requires effort, too tight is bad :) techt, but nae too techt :). I would definitely buy an appropriate socket and a torque wrench, this is not the last time you'll be taking a plug out.

More often than not you'll be able simply to clean the plug with avgas a wire brush and a wee bit of metal to pull the crud out. Replacing them with a new one is expensive and rarely necessary :).

**** TOO LATE ****

I would be very hesitant myself to change a plug without having received instruction in doing so by a certificated mechanic.
Legal does not always mean wise, FAA-land or EASA-land.
Tinkering with the ignition on my car I dont mind, if it stalls at the end of the driveway it wouldn't kill me.
Just a future recommendation; there is a bunch of stuff you are legally allowed to do as an owner. Take this list and decide what is likely to occur to you considering the type of flying that you do, unattended farm strips.
Take some instruction from a mechanic and carry the basic tools to do:

• Tire change or tire repair
• Plug change or cleaning
• Oil change
• Basic fabric patch
• Battery charging or replacement
• Landing/taxi light replacement