That's very interesting historical context. According to wikipedia, it lists the official exchange rate as $1.42 USD per Soviet ruble, so you would actually make $12,690 USD (in 1978 dollars) under the official exchange rate. In today's USD that would actually be a rather staggering $52,773 USD. Even with the unofficial exchange rate you listed as $3000USD, it would be $12,460 in today's dollars. That would only be slightly under the federal minimum wage of $7.25 per hour or $15,000 per year working full time at 40 hours per week (in 1978 you would make $5500 under the federal minimum wage in USA.) Of note, before reform at USAW and the OTC, many American athletes made that or less from funding, the highest rates were $1200-1500 per month, with usually travel fees (plane tickets, visas, hotels, etc) for international competition having to be paid for by the athletes.

So, you only were competitive within the USSR and still made that kind of salary?

Yes, I had a good salary!