I think 1 gp = 1 xp in 5e D&D can work with the regular 5e XP table, but the DMG treasure hoard tables would need some tweaking; at high level XP to level is almost flat, only about 1/10 what a 1e-2e PC needs, while the hoard tables give tens of thousands of gp at 11-16 and hundreds of thousands at 17-20. I think the 1st two Tier tables work ok, but Tier 3 should only be twice Tier 2 not 10 times, and Tier 4 should only be four times Tier 2 not 100 times.
Tier DMG Award Suggested Award
1 100s 100s, eg 500gp
2 1000s 1000s, eg 5000gp
3 10000s 2000s, eg 10000gp
4 100000s 4000s, eg 20000gp
Another way to look at it would be to base typical treasure hoards off the Monster XP table, which is already tailored to PC XP-to-level:
Tier XP award (GP/XP)
1 200-1100
2 1800-5900
3 7200-15000
4 18000-25000
That matches up pretty close to my intuition for Tiers 3 & 4.
Magic item sale values would need to be tweaked similarly if magic items give XP, eg:
Rarity DMG List Value > Tweaked Value (DMG) >Retweaked value (XGTE)
Common 100 100 100
Uncommon 500 500 400
Rare 5000 5000 2000
Very Rare 50000 10000 10000
Legendary 500000 20000 25000
Uncommon 500 500 400
Rare 5000 5000 2000
Very Rare 50000 10000 10000
Legendary 500000 20000 25000
Update:
When converting OSR adventures to 5e D&D, GP values are likely to need tweaking, since 0e-2e XP requirements to level tend to be around x10 5e (although the disparity is less at mid level), while monster XP values are low. Dividing treasure amounts by 10 should work ok.
