The five-year-old won three of his four starts over hurdles last season, but this Grade Three event was a completely different level to races won at Newcastle and Catterick.
He had hinted he belonged at this level when a gallant second in last month's Silver Trophy at Chepstow, however, and dominated his rivals under an enterprising ride by Joe Colliver.
O'Keeffe said: "I was a bit worried turning for home as I wondered whether they'd come and catch him, but he kept going and I thought he was given a beautiful ride."
Colliver took the bull by the horns from flag-fall aboard Sam Spinner, quickly settling into a rhythm out in front.
The Dutchman briefly threatened to make a race of it in the home straight, but 6/1 shot Sam Spinner eventually propelled himself 17 lengths clear in the Merseyside mud.
"He's improved from Chepstow and we thought he would, not so much physically but more just in terms of his education," O'Keeffe added.
"He's been a slow learner and a big baby, but he's obviously getting there now."
Asked about future plans, the Leyburn-based trainer said: "We're going to have to discuss it.
"We were thinking about the Coral Cup (at Cheltenham) or maybe trying to qualify him for the Pertemps Final.
"Maybe we'll have to aim a bit higher now. I don't have many jumpers - he's the best I've had - and it will be exciting thumbing through the programme book.
"We could look at the Long Walk at Ascot, but is that aiming a bit high?
"I'm a bit out of my comfort zone, to be honest. We have five or six jumpers and this is new territory for me."
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