50mm stem 20mm of spacers below it
I’d start by sticking the spacers above the stem, which’ll put slightly more weight on the front end. If you have a high rise bar on it, you could always swap for a lower rise or even flat one again to put more weight on the front end. You can also move the saddle forward, even go to an inline seatpost rather than a layback if that’s what you have already. A longer stem’ll do a bit of that too. The balance is between the bike fitting you and the weight distribution working.
Basically you’re trying to lower the front end so more of your bodyweight goes onto it. It may also have the advantage of increasing front end grip all round. You could reduce fork travel or fit a fork with a lower A/C measurement, but the obvious starting point is to drop the stem and maybe move the saddle forward and see where that gets you. Five minute job.