Negotiating With Home Seller to Replace Furnace?

I'm trying to purchase a home with a furnace that failed inspection. I would like the sellers to just give us 10k back to replace the furnace and let that cost go in to the mortgage, but lenders do not allow that. I'm worried that if I have the sellers replace the furnace that they will opt for the cheapest thing they can possibly find. Is it unreasonable to negotiate that a certain company, and a certain type of furnace needs to be installed? I can take a higher mortgage, and they can take the money from the sale. Is that possible?

Thanks
Added (1). The reason the cost is so high is because it is a gravity furnace that contains asbestos and has potential to leak carbon monoxide into the home.

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