The 20-year-old frontman struck his 50th goal as a professional in just 73 games in Sunday's 1-0 win over Hearts in Perth.
And his reward for his incredible scoring record was a call up to the Scotland Under-21 squad that will face England at Bramall Lane next Tuesday.
May has already notched up the crucial goal which knocked Norwegian heavyweights Rosenborg out of the Europa League this season.
And team-mate MacLean believes the striker is ready to shoot his way to a full call-up after bulking up his skinny frame following loan stints with Alloa and Hamilton.
The former Aberdeen and Sheffield Wednesday forward told Press Association Sport: "Stevie has been fabulous since he has come back into the side. He's been a breath of fresh air.
"He is scoring goals - which he always does - but he has also added something to his game too. Hopefully the two of us can continue to build our partnership.
"He has bulked up as well and he looks ready to play in the SPL. Hopefully he can keep going and get some more goals. He's a young guy and I'm sure he can on and play at the highest level and even for Scotland."
MacLean struck an all-important away goal for Tommy Wright's Saints in last week's third qualifying round first leg against FC Minsk in Grodno.
The Belarusians jet in tomorrow ahead of Thursday's return in Perth, but given May's impressive start to the season, MacLean admits his place might be under threat.
"Whatever way the gaffer goes for Thursday, Mayso has done himself no harm with his goal against Hearts," he said.
"He might even start with Stevie up on his own instead of me, I don't know.
"If Stevie keeps playing the way he is, I'm sure he will continue to be in the side week in, week out.
"So far our partnership is looking good, though. We seem to link up well.
"In the first half against Hearts, we seemed to cause them a lot of problems. I was close to getting in on the rebound to one of his shots as well, so it is working well for both of us.
"It's been easy to work together. Whenever good strikers link up they seem to know where each other should be and that's the way it has been going so far."