I have a 1979 Yamaha DT175MX 1979. Two failed attempts with eBay at buying the wrong cable. The connection for the Oil pump seems to be different than all other models for some reason. My question is, if I just don't connect the oil pump cable would that make the oil pump obsolete or do I need to do something else as well?And if you are in London, England. Could you recommend  a store I can visit and actually inspect the parts I need to

What I might do if in a similar situation & wanted to go riding. Just premix at say 30-1 & leave oil in the oil tank which will keep pump lubed plus deliver a minimal amount at minimum stroke. That's while you're trying to find the correct cable. That's just an easy option for now so you can go riding. Maybe could go leaner than 30-1 with modern trick oil but I'm not up on that although others will be on here. One thing I'm not a fan of is without pump connected the throttle will feel very light but up to you or find a heavier spring. Be sure the cable your using is as nice & free as possible.

Go to Yamaha and purchase the complete 80-81 DT175 cable.  It has a new and improved splitter and fits the 1978-79 models perfectly. 

Last time I bought one, all parts were still available new and the whole thing was around $50 US. 

P.S.  Are the threads on the oil pump cable wrong?  That's an "aftermarket cable" issue I've seen with even the older DT175 twin shock cables.

That would be the perfect option if the bike actually started haha. I connected the throttle cable to the carb and oil pump but it's still not kicking over. :(

Heres a picture to show what I mean by the oil pump cable not connecting.I was just working on it and the throttle cable is working and the jet needle isn't stuck. The spark is sparking. I don't know how or what else could be stopping this bike from kicking over.

Photos have to be uploaded via a third party hosting site such as Imgur.

The plot thickens, but we're here to help!!. Yep, pics by external source.

Clean the carb.  Pay attention to the starter jet in float bowl and pilot jet. 

That model is almost impossible to start if the float bowl jet or the tiny 22.5 pilot jet is restricted. 

P.S.  I'm pretty sure your bike is "kicking over" (aka "turning over").  If it wasn't, then the engine would be seized or something and you wouldn't know it had spark.  I'm pretty sure you meant the engine isn't starting/running? 

Oil pump cable on the 79 is a push fit into the pump chamber housing and held in place by tension on the cable and an R clip, not threaded into the case. 
Lower cable assembly part number 2A62631200.  Discontinued and very hard to find these days.  Mark T is the expert so if he says the 1980 cable will fit, then...
yambits.co.uk/dt175mx-throttle-cable-1980-1981-p-18693.html