So the problem that you have is that while the data is technically targeted, I'm going to guess that it is aged data because of the size. So really it's no longer targeted, because it's not fresh data, so it's unlikely the user is still seeking the info that he was at the time the lead was generated.
So in this case you don't want to use a service like Aweber, because the cost to send will be too high, because it's not targeted and the response rate will likely be very low. Additionally aged data is more prone to getting complaints and you would likely just get the account terminated.
So you are going to need to mail using IPs. However most all of the services that exist, that say you can mail purchased lists are just a scam to take advantage of novice mailers and overcharge them for IPs.
You are going to need to get IPs from a provider that supports mailers and won't terminate the account for complaints and will replace the IPs ad needed if you end up getting them blocked / blacklisted.
Additionally you need to get the list cleaned by a reputably email hygiene company that will remove bad addresses, know complainers, spam traps, etc... The big risk is getting the IPs blacklisted by spamhaus as most providers will take a very dim view of you, if it happens.
Nothing about this process is cheap. Do you have a budget?