The Paisley men will have to handle the Rugby Park poacher with care when they travel to Ayrshire on Thursday as Boyd looks to build on his 11-goal tally.
McGregor is preparing to go head to head directly with the former Rangers striker for the first time but has no doubts the 30-year-old is good enough to return to international action.
Boyd was handed a Dark Blues recall by Gordon Strachan for the November friendly with Norway after a three-year wait but was left on the bench as the Scots ended 2013 with a 1-0 win.
However, Buddies centre-half McGregor said: "I think Kris is good enough to become a Scotland regular again.
"You judge a striker on his ability to put the ball in the back of the net and his record speaks for itself.
"He's so dangerous and is on top form right now. He deserved his call up for the Norway game and will probably feel disappointed not to have been given a run out. But he can definitely be an asset for us if Gordon Strachan decides to use him from the start."
Boyd was sent off the last time the sides met in August after lashing out at Saints skipper Jim Goodwin.
McGregor played at right-back that day but will be positioned at the heart of Danny Lennon's defence for Thursday's meeting and cannot wait to get to grips with the Scottish Premiership's record scorer.
"I've not actually played up against him before," said the former Cowdenbeath man. "The last time we played Killie a few months ago I was at right-back, but I'm looking forward to pitting my wits against him this time.
"It will be interesting - a battle that I'm eager to get involved in. He's a goalscorer and probably one of the all-time greats of the SPL.
"It will be good to test myself against him. I won't be able to give him a minute's peace. If you switch off, he looks for that and punishes you. You could play well for 89 minutes and he will score from your one mistake."