Espionage requirements
Liztown distance 1.05 factor
Culture 0.5 factor
Religion 0.6 factor (Liz must remain in Buddhism)
Espionage spending assume 1.00 factor (we might have some small discount for this)
Tech stealing factor 1.5
Stealing techs from Liztown is 0.4725 with no stationary spy discounts and 0.23625 with 50% spy discount
Trojan Horse distance 1.12 factor
Culture 0.5 factor
Religion 0.6 factor (Liz must remain in Buddhism)
Espionage spending assume 1.00 factor (we might have some small discount for this)
Tech stealing factor 1.5
NO stationary bonus 0.504 , 50% stationary bonus is 0.252
Tech costs
Compass 624

Optics 936

Machinery 1092

CoL 546
Likely scenario for espionage costs
Steal machinery in LizTown
1092 *0.23625 = 258

(approx) formula must truncate so factor calculation is always a small amount off
Steal compass in Trojan Horse
624 * 0.252 = 157
Steal optics in Trojan Horse
936 * 0.252 = 236
Steal CoL in Trojan Horse
546 * 0.252 = 138
Steal CoL in Trojan Horse with only 10% discount
546 * 0.4536 = 248
Convert Liz to Hinduism with 50% stationary discount in LizTown
600*0.1575 = 95

with 10% stationary discount it would be 170
So if we get a great prophet we would need to steal machinery, compass and optics at the very least so we need a minimum of 651
on the turn we ceasefire with Liz to cover those steals.
If we want to prepare to steal up to optics and CoL we need 789

on the turn we ceasefire with Liz.
If we want to steal 3 techs then 2 turns later steal CoL and flip her to Hinduism with 10% stationary spies we would need
651

on ceasefire turn
Then we would an additional 418

2 turns later.
Might be tough to get all of this espionage and have enough gold for upgrades...
Might be tough to get the espionage even without storing gold for upgrades.
Other numbers
a civil service steal at 10% stationary bonus in Liztown would be 530