its all trial and error, get yourself a good temp gun extremely important, every enclosure will be different for heating requirements, pending substate, cage furnishing, glass or wood terraium, how much ventilation, how far is the basking spot from the globe, what material is the basking spot there is so many variances, over the years in exp
i have found in a larger 1200x 650 h x 600 deepenclosure i just use a PAR38 120wat flood phillips other brands are crap and dont have a good reflector to give nice radiating heat underneath the bulb, and i use so i can adjust with the dimmer and a temp gun so i can get a precise basking temp,
smaller enclosure i use nelson par 20 50wat 600x 350 h x 600 deep, all nelson bulbs are crap except this specific bulb
my enclosures are pine, reason for using the dimmers i can adjust the temp by dimming the light to what i need saves messing around finding a bulb that may or may not work in the cooler months etc etc
hope this help this is the light/s set-up i use in multiple enclosures and have done for many many years now and have worked extremely successfully for me, if you do so make sure the dimmer can not be moved or altered by anyone even by accident otherwise your basking spot can turn to a hot grill spot,
best of luck a temp gun is your best freind and just buy bulbs a few different sizes if you keep the receipts i know bunnings let me take them back,
