OMFG - just don't.

1. Not all rims are created equal - you can't just select rims based on what you see as the catalog weight. You make tradeoffs in feel, durability and performance that a catalog won't explain to you. You don't mention your weight....spoke count of existing wheel, etc. Building ANY wheel without first addressing the specific rider weight FIRST is a recipe for failure.
2. You're trying to save money on the spokes? Then don't change the rim. It's not worth it. If you don't have the budget to spend $30-$60 on spokes then why in the heck are you even remotely thinking about changing out a good Mavic rim for a flimsy climbing rim.
3. Change the spokes. Change the spokes....change the spokes......oh and especially the nipples too.
4. What are you trying to achieve again? Oh yeah...you want a new wheel but you only want to change the rim....Do you have the tools needed? Do you understand how tension affects a spoked wheel system? Do you understand how it's a tradeoff between the natural imperfections in the rim combined with the imperfections in the spoke and the hubs?


...so why are you wanting to change this again? You think it will be "easier to spin up"? How is that going to "help" you with a problem you are currently having?

If you want to do it for the challenge of doing it then yes...go for it. Learn and have fun. If you are asking because this is a serious pursuit by you to somehow make your setup better....I would highly encourage you to simply ride what you have until it breaks. Especially if you are trying to save money.