The hardware and shell design, along with lack of strength in the wood is not designed to sound like a conga, nor can it sound like a conga. It wont be able to take a thicker skin like a conga would take, nor would the shell withstand the tension from the hardware, the lugs wont be able to deliver the tension needed also from a thicker conga skin, be it cow, buffalo, steer, mule etc etc The drums would make ok Candombe like drums... and only just. My advice is, if you want conga like sounding drums, look towards investing in some congas.
Below are some pics of my 'Chico' from the set of 3 Uruguayan Candombe drums, a student gave me this drum as a gift a few years ago. The chico is the smallest drum, the time keeper. While the Piano drum provides the base and low tones, the Repique as its name suggests, is the soloing drum, while it solo's around a base solo pattern.
It is made of Brazilian Pine and the skin is goat.