Are you just waiting on shipping for those coolant lines or did the other person fall through?
if you run those lines, you'll also need 2 special hoses at the rear. The lines end back towards the firewall, much lower than than the heater core. The factory hoses then loop up like a roller coaster to connect to the heater core. Also, the back of the lines attach using one of the lower intake mounting bolts with a special bolt/stud fastener. If you didn't use the bolt/stud fastener in the right location, it's not the end of the world, but the only thing holding the lines down will be the fitting at the front.
I see you already found a brass fitting collar to go in the lower to plug it. If those lines fall through and/or you don't feel like messing with those heater tubes, you can very cheaply put together a solution with brass fittings and some heater hose.
I ran in to a problem where the stock lines wouldn't fit my intake, and someone else posted a picture of their solution which I'll share here. They used a T fitting to provide a spot for the ECT as well as allow a run to the heater core.
My solution is slightly different because my aftermarket water neck has a provision for the ECT, so I just used an elbow and a barbed fitting.
elbow
barbed hose fitting
mocked up
Here are what the heater lines look like, you can see the bracket on the back where they bolt to the lower intake manifold. SN95 style is on top, foxbody style is on the bottom. They place the ECT in different locations. Please excuse the mangled foxbody bracket.
if you run those lines, you'll also need 2 special hoses at the rear. The lines end back towards the firewall, much lower than than the heater core. The factory hoses then loop up like a roller coaster to connect to the heater core. Also, the back of the lines attach using one of the lower intake mounting bolts with a special bolt/stud fastener. If you didn't use the bolt/stud fastener in the right location, it's not the end of the world, but the only thing holding the lines down will be the fitting at the front.
I see you already found a brass fitting collar to go in the lower to plug it. If those lines fall through and/or you don't feel like messing with those heater tubes, you can very cheaply put together a solution with brass fittings and some heater hose.
I ran in to a problem where the stock lines wouldn't fit my intake, and someone else posted a picture of their solution which I'll share here. They used a T fitting to provide a spot for the ECT as well as allow a run to the heater core.
My solution is slightly different because my aftermarket water neck has a provision for the ECT, so I just used an elbow and a barbed fitting.
elbow
barbed hose fitting
mocked up
Here are what the heater lines look like, you can see the bracket on the back where they bolt to the lower intake manifold. SN95 style is on top, foxbody style is on the bottom. They place the ECT in different locations. Please excuse the mangled foxbody bracket.