Well, you asked the "best way" to invest $300,000, and then you proceeded to limit yourself to two very poor choices.
Do you want advice on the poor options you presented? Or do you want the "best way"?
On top of that, there are a couple of critical questions. The first is: What's your goal? Is it appreciation? Cash flow? A combination of the two?
If you want cash flow, buy some cheap properties in Baltimore, Buffalo, or Cleveland. Maybe a few other places, like Spartanburg. You can pay $20,000-$50,000, maybe a bit more, and cash flow several hundred dollars a month. That's a very nice return on investment.
If you want appreciation, then you'd buy so-called "bread and butter" properties in areas that are economically strong. Or there are plenty of other ways, too.
Another critical question: What are your other finances like? Real estate is great, but you don't want to put all your eggs into one basket. Diversify some.
Another question: What's your tax situation? One strategy may be better than another, depending on your tax situation. Work with a good accountant.
And consider putting some of that money into a self-directed IRA. That'll allow you to invest in real estate (or other investments, such as notes and mortgages) without having to worry about taxes and capital gains. So, you'd be using the same money, except now it's sheltered. Again, your accountant can advise you. Or look up "self directed IRA" online. There are 4 or 5 major companies, all quite good, that can help you.
Now we get to your specifics.
Why would you want to pour $300,000 of your own money into a property. And not multiple properties, but just one? Bad, bad, bad idea. Sure, you have more negotiating power with cash. But not enough to compensate for the risk, for putting all your eggs into one basket. Really bad idea.
You want to buy properties for cash? Then consider the cash flow scenario above, and sink $20,000-$50,000 into one or two properties. But you don't even have to do that. Again, your accountant can advise you on the tax consequences, but you can put 20%-30% down, get financing on the rest, and still cash flow.
You ask "Is it good idea to buy an old victorian house"? If you want to live there, fine. But as an investment--no, of course not. As an investment, you look at the numbers.
You ask about buying a newer house to rent out as an investment. Maybe, so long as you don't overpay and so long as you've got positive cash flow. Again, it's a question of numbers.
You say you're a house manager. Then perhaps you'd want to look into buying a smaller multi-unit building--for instance, a 4-8 unit apartment building.
But use leverage. Don't sink the entire $300,000 into one property. Bad, bad idea.
Contact several Realtors in the general geographic area you'd like to invest. Look for Realtors who at least claim to know something about real estate investing. Ask what their strategies would be. Then run those strategies past an accountant to see whether they're viable from your financial standpoint.
Hope that helps.