Sir John and prospective owner Anton Zingarevich, whose takeover was due to be completed in March, have big plans for the Royals following their return to the big time, which was secured by a 1-0 home win over Nottingham Forest on Tuesday night.
Promotion could be worth as much as £90million to the Berkshire outfit, who need a maximum of four points from their remaining two games to clinch the npower Championship title, but there will be no wild spending.
Sir John told BBC Radio Berkshire: "I have put a lot of money into this football club, which I'm quite happy about.
"And I hope the Zingarevich family will take Reading on to a different level and into Europe and beyond.
"It's all well getting to the Premier League, but you need deep investment to stay there. We have found very pleasant people in the Zingarevichs, who will continue to do things the Reading way.
"It bodes well for Reading and I hope they will take the club much further.
"I'll be staying on as chairman. If anything, it [the takeover] is a fantastic insurance policy.
"We will strengthen as we see fit. We have already strengthened and that will carry on.
"What I don't want is people thinking Reading are an open cheque book. We will be as careful as we have been in the past."
Reading, of course, are now worth significantly more than when Sir John agreed a price with Zingarevich back in January, but he will not try to seek a better deal.
He said: "The club is more valuable now, but I have struck a deal, and a deal is a deal."
A delighted Zingarevich, who hopes to finally complete his takeover imminently, revealed planning for life in the top flight is already under way with plans for player recruitment and a potential extension to the 24,000-capacity Madejski Stadium in hand.
He told BBC Radio Berkshire: "The Premier League is where you want to be as a football club owner.
"I think there is a lot to develop here, but the infrastructure that is already in place is key.
"We have already started looking at upgrading the Academy and the training facilities.
"If we stay up the first year, then we will upgrade the stadium. There are a lot of things to do, but there is a lot of potential."
Director of football Nicky Hammond will work hand in hand with manager Brian McDermott as the club attempt to develop on the pitch, and he too is expecting evolution rather than revolution.
He told Sky Sports: "There are two games to go and we are top, and we want to stay there. In the first instance, that's the most important thing.
"Then we will sit down over the next couple of days and start to look at the numbers and plan going forward.
"But it will be the Reading way. We always do it in a sensible fashion, not cavalier.
"In my conversations with Anton over the last number of weeks, I don't anticipate that will change too much, really."
Tuesday night's win sparked massed celebrations on the pitch and in the home dressing room, where one man decided he could not miss out.
Midfielder Jem Karacan started the night in hospital after undergoing surgery to repair his broken ankle, but was determined not to miss the celebrations.
He told Sky Sports: "As soon as I knew we had been promoted, I said, 'Right, get me out of here'.
"I asked the nurse to discharge me - I don't think she was too pleased about it - and my mum took me down to the stadium.
"I was pushed in the wheelchair into the changing room and saw all the boys, and that was it, really, the best day ever.
"A little tear came to my eye. My sister was screaming more than me, I think, and my mum. They were just absolutely delighted.
"Noel [Hunt] wheeled me through in his pants and just seeing all the lads, it was amazing, the chairman, the new owner - it was just brilliant to see the gaffer.
"It was just the best feeling ever."