u/FutureA350

Im trying to make an E bike out of my 29" Huffy rock creek bike. My bike currently weighs 35lbs and i myself weigh 125lbs. Im trying to get a range of ~40 miles. Not trying to go fast i specifically want to go 15-20 mph.Ive been looking at ebike conversion kits and i might be going with 500W 48V because i think that might be the best for me im riding on mostly flat terrain. Can you guys give me recommendations for what battery i should get.Any e bike conversion kit recommendation. Im going with 450 bucks as my budget (for everything included). Tips are also appreciated im just a beginner.