It's not just the weight, you need to look at the dimensions also. The WS-10 is a massive engine. It will reduce your fuel load and unnecessarily increase your empty weight by 1T.
Single engine version will be inferior to the twin engine version if you are using the WS-10.
And you first need the engine before you start testing. And this process takes years, a decade at least.
Then only option left for Pakistan is to use twin WS13A of 200KN but then J31 already got them. So whats the big deal of joining TFX, Nothing, just go n buy j31 . Yayee we got the engine which made for us only
Now lets start making TRX or i mean TFX
World Turbofan Aircraft Engines
19 tons (or 190 KiloNewtons) of wet thrust (which means with afterburner)
19.1 tons (for F-35/JSF) - Pratt & Whitney F135 (in service 2009 - dates are approximate).
Important note: F135 has a high bypass ratio and F-35 cannot supercruise.
18 tons of wet thrust
18 tons (for J-20) - China's WS-15 ("Initial Operational Capability"/IOC 2020. Successful prototype operation in 2005). WS-15 has a low bypass ratio and J-20 can supercruise.
15 tons of wet thrust
15.6 tons (for F-22) - Pratt & Whitney F119 (IOC 2004). F119 has a low bypass ratio and F-22 can supercruise.
15.5 tons - China's WS-10G (Global Security believes it was installed on J-20 prototype in 2011)
14 tons of wet thrust
14.5 tons (for T-50/Pak-Fa) - AL-41F (in service 2010)
13 tons of wet thrust
13.2 tons (for J-10, J-11, and J-15) - China's WS-10A (in service 2009)
13.2 tons (for Russian Su-30) - AL-31FM1 (in service 2007)
12 tons of wet thrust
12.5 tons (for J-10A) - AL-31FN (in service 2002)
8 tons of wet thrust
8.9 tons (for Eurofighter Typhoon) - Eurojet EJ200 (in service 1991)
7 tons of wet thrust
7.5 tons (for French Rafale) - Snecma M88-2 (in service 1996)